There are two parts to this project, building the box and making the inlays. They can be built in parallel, but for the sake of clarity, I’ll describe them in sequence.

The Inlay:

Pick contrasting colors for the strips. I used Red Cedar, Oak, and Walnut.

The thickness of the stock will determine the maximum height of the bows. I had 3/4 inch stock, so I glued two boards together to make 6/4 boards.

To ensure the strips are all the same width, make a simple jig from a piece of scrap wood. Cut a notch at one end of the scrap wood where the Cedar and Oak will rest when sawing it.

After the Oak and Cedar strips are cut, stack them in an alternating pattern and glue them together.

When that dries, square up the new board.

To cut the stripes I cut 45-degree angles into a couple pieces of scrap wood and clamped them to my table saw sled just like you’d normally clamp a stop block in a table saw sled. Sit the striped board snuggly against that stop block and rip the board into pieces about 1-1/2 inches thick. If you want your inlay to be thicker or thinner you can adjust this cut accordingly.

To accentuate the inlay, cut some veneer strips on the bandsaw. I used Walnut and Oak.

Glue and clamp the veneer to the sides of the candy cane striped boards.

When those dry, square up the new boards and cut the inlay on the band saw.

To cut the ribbon, tape the template provided to the sides of the candy cane striped blocks, and use a scroll saw to cut them out. I made six ribbons and chose the four best ones.

Cut 45-degree angles on the ends of the ribbons where they’ll touch.

The Box:

This is a pretty basic box, cut 5 pieces of 1/2 inch boards to size. The bottom will be made from 1/4 inch oak plywood.

The dimensions of the box I made are

7-1/2 inches long
5-1/2 inches wide
4-1/2 inches tall

Adjust those to whatever size you want.

Cut a 1/4 inch rabbet in the bottoms of the 4 pieces that make up the sides.

Use a large chamfer bit in your router to cut miters on the edges of the sides and top.

Glue the edges of the sides and tops and use tape to clamp them together.

Measure the exact size of the bottom, cut the oak plywood to size, and glue it in place.

When the box dries, use a trim router with a flush cut bit to cut notches for the inlay.

Use a table saw to cut the top of the box off. Don’t cut completely through the top because it’s easy to damage a corner of the edge after the top is free. Instead, cut about 90 percent of the way through the lid and finish it with a hand saw.

Attach the hinges.

Glue and clamp the inlays in place.

Glue the ribbons on top.

Finish the box with oil to make the contrasting wood colors stand out.

Building a step stool is obviously a simple project. The circuit is also extremely simple but it can be used to drive robot motors, water pumps, or high voltage lights from a Raspberry Pi or Arduino.

Parts

2N2222 transistor
PIR sensor
LED Strips
1/4 inch neodymium magnets
5-minute clear epoxy
20 gauge flexible wire
2 x 4-AA battery holder

The Wood

Here are the rough dimensions of the wood, but these measurements were taken after the project was finished.

The top was 12″ by 7″
The total height was 7″
The width of the bottom of the leg was 8″
The legs were splayed out at a 10-degree angle.

The only measurement that’s important is the ratio of the top platform to the base. Make the base about an inch longer and wider than the top so it won’t tip over. Decide how big you want the top then cut the legs accordingly.

The Cross Beams

The center cross beam is made from three parts, the center beam, and two pieces that are attached to either side of the center beam.

Carve out the middle of the center beam and cut tenons on the ends.

Use the center cross beam as a pattern for the other two. Cut a mortise in these, but don’t cut all the way through. When the three pieces are placed together, there should be a hollow center.

The Step Stool

Glue all the joints and clamp everything. Only glue one side of the center beam. The other side will be the access panel used to install the electronics and change the batteries.

After the glue dries apply whatever finish you want. I don’t really like stains, so I just used a simple oil finish.

The Access Panel

Drill small recesses on the inside of the center cross beam and loose cross beam.

Mount the magnets in the holes with epoxy.

The Circuit

Attach the LED strip to the center cross beam. Drill a small hole at one end large enough for a red and black wire. Solder the wires to the led strip and cover the exposed solder with some hot glue.

Measure the diameter of the PIR sensor and drill a hole through the center of the cross beam covers. Screw or hot glue the sensors in place.

Solder the parts together as shown in this diagram

The Shadow Box

You should build the shadow box first because that will give you a frame of reference for the sizes of the other parts.

Measure your window for the width and height that work best for you. My project ended up being about 33 inches wide and 58 inches high.

Cut the plywood to the height and width of your project.

The shadow box should be about 2 inches deep, so rip 2x4s or 2x6s down to 2 inches by half an inch. Then cut those to whatever length they need to fit on top of the plywood.

I used a simple butt joint for the frame. The plywood backing will keep the project square and sturdy.

Paint the frame black.

Cut Out Silhouettes

There are four silhouettes in this project.
1) The big spider
2) The little spiders
3) The captured kid
4) The jagged border

You could do this project with foam core, but it would be more fragile, and I don’t think it would last many Halloween. If you have a scroll saw, I recommend cutting all the silhouettes out of thin plywood.

Transfer the images to the plywood. The small spiders can be printed and glued to the plywood. The larger spider will have to be transferred manually. If you don’t feel comfortable freehanding the drawings, you could draw grids over the printed images and the plywood, then draw the image one square at a time.

Freehand the jagged border. There are no templates for this one, just draw and have fun.

After the images have been drawn cut them out with an Exacto knife or a scroll saw.

Assemble the Border

Assembling the border is pretty simple. Grab a couple pieces of the border and trim the edges so they match. Then glue a piece of scrap wood on the back of the joints.

Attach the LEDs

Put 2/3 to 3/4 of the lights on the spider, and the rest of the lights on the girl.

The LED strips have tape on the back, so they’re easy to attach.

After you’ve placed the LEDs where you want them, cut wires to fit between the spaces and tape them down with masking tape. After you’ve soldered all the connections, use hot glue to cover the exposed metal.

Draw Web

Cut the paper to fit inside the frame. Use spray-on adhesive to hold it in place.

Use the fine-tipped marker to draw the spiderweb. Start with a dot as the focal point, then draw a few radial spokes from there to the edge of the frame. Draw a few droopy strands as well. Then add some connections between the main support strands. Some should be nice and tight, and some should be droopy. Finally, to give it character, use the two larger markers in random places. Varying the thicknesses of the lines gives the web a more cartoony look that I like.

Attach Silhouettes to Box

The little spiders are easy. Just glue them directly to the paper.

The big spider isn’t too much harder. Cut some small blocks to act as standoffs and glue them to the back of the spider. Where the spider’s legs get close to the frame, attach a block that is glued to the frame, to the back of the box, and to the spider legs.

To hang the cartoon girl upside down we have to build a small adapter. Grab some scrap lumber that’s at least a few inches longer than the width of her base and make a U-channel on the table saw. The character’s body will sit in the center of the U-channel. You’ll need a flat area to screw this U-channel to the project’s frame, so use a saw to cut the walls off the ends of the U-channel so you have a flat stock on the ends.

Attach the character to the U-channel with screws, then screw the flat part of the adapter to the top of the frame.

Finish the Wiring

Run wires from the girl and the spider along one edge of the frame. Hot glue the wires in place and paint them black. Drill a discreet hole in one corner and run the plug through that. Solder all the wires together and use heat shrink to protect everything.

Attach The Border

Find or cut scraps about 1/2 an inch square and about 3-6 inches long.

Measure the thickness of the border. Draw a line on the inside of the frame down from the top of the box that is the same depth as the thickness of the border.

Glue the scraps around the frame along that line and clamp them in place.

When the glue dries, remove the clamps and set the jagged-edged border on top of the blocks.

Trim the Shadow Box

Rip some strips of lumber about 1 inch wide and about 1/4 inch thick.

Cut those to match the height and width of the frame. Miter the ends, and paint the strips black.

When the paint dries nail the trim on top of the border.

Dimensions aren’t critical because the vertical slats are intentionally staggered.

All the lumber is 3/4″ thick.

Cut 5 pieces approximately 5.5 inches wide by 24 inches long.

The shelf is about 3.5 inches wide. You won’t know how long to make it until after you assemble the back. You could try and do the math then make your cuts perfect. But, I promise you’ll be a bit off. The best way to make it look perfect is to rip the width now, then cut the length after you’ve assembled the back.

The back is held together by two horizontal pieces that about 2 inches wide and about 2 inches shorter than the width of the 5 vertical slats. A rough estimate would be (5.5 * 5) – 2 = 25.5 inches. Don’t worry about being perfect. Those pieces will be hidden on the back so they just need to be a little shorter than the width of the whole shelf.

The shelf is hung with a french cleat. When you cut the horizontal pieces for the back, spit one of them at a 45-degree angle. One half will be attached to the shelf. One half will be attached to the wall.

I know those numbers aren’t precise, but that’s how I work. Cut it close, then make it fit.

The biggest challenge when carving the silhouettes is adjusting the images so a small bit — a 1/16″ diameter flat end — can carve out the details. The stars on the flag are the hardest part, so program the CNC machine to go very slowly around the delicate parts.

For the most part, painting in the silhouettes is easy. If you make a mistake, you can sand it out. The stars are the exception. They’re too delicate to sand, so you have to get it right the first time. Use a fine-tipped brush, go slow, and stay focused on the task.

Everyone has their own favorite way to finish wood. Even though the wood cuts were all estimates, I felt this project deserved a silky smooth finish, so I spent a little more time on the finish.

Mix a batch of about 50% oil based satin polyurethane and 50% mineral spirits. Put on 5 to 6 coats and wait about 12 hours between each — A coat in the morning before work, and a coat at night before bed. The last coat is 100% polyurethane, and you should let it dry for a full 24 hours or more.

Stagger the shelves however you like then draw a line so it will look like the soldier and the flag are standing on the shelf. Keeping the boards square is critical. Transfer that line to the back of each piece, then flip the whole thing over making sure you keep the wood in the right order.

Attach horizontal pieces with screws and glue.

Cut a dado in the front of the piece for the shelf. This really isn’t necessary, but it will help keep everything square as time wears out the screws and glue.

The lumber for the shelf was 3/4″ thick, so use a 3/4″ flush-cut router bit.

The straight edge of a piece of MDF can be used as a template to keep the router straight. Set the router to cut about 1/4″ deep.

Cutting into the face of a nearly finished project is always a bit scary. So double check everything . . . twice.

Attach the shelf with glue and clamps.

The key to French cleats is hanging them level.

Put one screw through the lower half of the french cleat and make sure it goes into a stud. Put the shelf on that, and adjust the shelf so it’s level. Mark the edges of the cleat, remove the shelf, and add whatever kind of drywall anchors you think are best.

The design is the most subjective part of the build. I went through several iterations before settling on this design.

Here are a couple other ideas I considered that you might like:

1. Make the backcross section less abstract. For example, I drew a few sketches of dragon wings and bat wings.
2. Use horizontal stabilizers or even a solid platform for the mouth area that the laptop rests on. This would increase the stability of the stand if your design is taller than mine.
3. Rather than having two vertical pieces, have one in the center which has horizontal pieces extending from the mouth that the laptop would rest on. The back/wing section would also have to be tweaked to add extra stability. I really like this idea because it would look more like a dragon flying out of my desk with a laptop in its mouth. But you’d have to spend a lot of time thinking about how to reinforce different pieces to make sure the whole thing is stable.

Pro Tip: I made this out of 5-ply Birch plywood. Don’t do that. The pointy parts chipped off in a few places. Use a nice solid piece of wood.

I used Gimp to draw the part, and Fusion 360 to extrude the drawing and generate the gcode. I’m a software developer and I prefer to support open source projects whenever possible, but I have to admit Fusion 360 is pretty nice. I’m pretty sure I could have drawn the part directly in Fusion 360, but I haven’t been using it long enough to have figured that out yet.

After the CNC machine cuts out all the parts, paint the glow in the dark blood.

I like the spray on glow in the dark paint better than the acrylic. It goes on smoothly, and it’s less visible in normal light, so it’s more surprising when the teeth start to glow in the dark.

Rip jagged pieces of painters tape to mask out the “blood.” The final result won’t look like normal flowing blood, but the sharp edges give it an evil fire blood kind of appearance.

Spray several light coats.

For the Slytherin badge, I grabbed a couple black lights to make it easier to see where the paint was going. That helped me put the paint on more evenly. My first attempt without the black lights was very splotchy, and looked so ugly I had one of those dark moments where you say things like: “Why am I doing this?! I have no idea what I’m doing. I should just give up.” So, I put it down and went to bed. The next day I tried again with the black lights and the results were much better.

To finish the piece, I used a couple layers of polyurethane. Nice and easy.

Snape . . . I mean, snap everything together, and give it a good home.

Now I have to figure out what to do for the other houses . . .

Powerlines were in danger of being torn down by a beautiful Ash tree, so my city had to cut it down. I saved a few pieces of the stump that were going to be chopped up into mulch. I’ve seen several tree stump side tables, but they all seemed a bit boring. The idea of having a fireplace in the middle of a tree made me laugh, so I carved a hole in the side, decorated it, and added LEDs that flicker like fire. Fairy gardens are cute, so I carved the fireplace with long sweeping edges like a fairy would. I topped the log with a tree made from glass beads, paint, and epoxy. Finally, I covered the sides of the trunk with a thin layer of epoxy to try an preserve the bark.

Instructions to complement the video:

Carve a depression in the top of the log a little deeper than the height of the tallest bead. There will be a thin layer of epoxy below and above the beads, so the depression needs to be slightly deeper than the bead’s height.

Draw a line all the way around the top of the stump about half an inch away from the edge.

Use a surfacing bit on a router to cut a smooth and even depression.

Cut a fireplace out the side of the log. A spade bit will quickly remove the bulk of the material. Then a chisel can be used to clean up the edges and give the shape a bit more character.

Pour a couple layers of epoxy into the depression you carved in the top of the stump. This will seal in the cracks and keep the air bubbles from spoiling the final image.

After the epoxy dries, arrange the beads and pour another thin layer of epoxy over them.

Draw/carve/paint the scene. I practiced on a sheet of acrylic to get the right look. I decided not to paint the tree trunk because the wood from the log looked better than any tree I could paint.

I’m not a very good painter, so I masked off the tree while I painted the sky. Then I masked off the sky while painting the grass.

Finally, pour enough epoxy to make the surface smooth. I did this in several stages to make sure the top was perfectly smooth and level.

To finish the fireplace, glue square beads across the bottom of the opening.

When the glue dries, lay the log on its back and coat the inside of the fireplace with epoxy.

When the epoxy dries, stand the log upright, and put the beads into the bottom of the fireplace. Pour epoxy over them and mix them around to make sure all the beads are lightly coated.

Drill out a cavity in the bottom of the stump to hold the battery pack container. I used an outdoor electrical conduit box. They can be found in the electrical section of any hardware store.

To simulate firelight, I used a theater prop sold by J2 LED lighting.

Solder a switch into the line, and mount the switch onto the battery pack container.

Drill a hole up through the bottom of the stump, and down through the back of the fireplace for the wire.

Thread the wire through the hole. Connect everything and close the box.

Seal all the bark with either epoxy or polyurethane. This will help keep the bark on the stump.

Place small sticks over the fire led and glue them in place

Grab a circular saw and cut the deck boards along the stringers. Then plane the wood to reveal the best lumber.

Joint one side of all your pieces. A simple table saw jointer jig will work best. If you don’t have one yet, it’s worth the time and effort to make a jig. I’ve created a small jig and a large jig and I use them several times a month.

Now that you have one straight edge, use it with your table saw fence to rip the acrylic and wood to the correct height.

Finally, use a table saw sled to cut all three pieces to the same length. You can easily get all three pieces to the same length by clamping a stop block onto the edge of the sled.

I used a CNC machine to carve my son’s name, but a scroll saw would work just a well.

After you have the name done, carve a line in the acrylic for the LED strip. It has to go all the way through the acrylic and be just a little bit thicker than the LEDs. The line should be near the bottom of the acrylic so it will be hidden after you’ve bolted the three pieces together.

Clamp the three pieces together and drill four holes near the corners for the bolts.

Drill a small hole in the back panel for the power cord.

Insert the bolts through the back plate and the acrylic.

The clamp on the LED strip will be too big to fit in the center of the assembled piece, so cut it off. Insert the power cable through the back hole and soldered the power cord directly to the LED strip.

Push the LED strip into the line in the acrylic, and put some hot glue on the ends to help hold it in place.

Finally, slide the front plate on, and attach the cap bolts.

Fun, Messy, and Challenging Activities for Smart Kids

The first time I explored basic electronics was building EON, my submarine Since then I’ve discovered making simple circuits on a breadboard is a lot like building a Lego kit; There are lots of little parts that turn into something cool when you

follow the instructions. And, my son enjoys blinking lights as much as I do. I wanted to make a quick project that would give us lots of time to play together, but rather than focusing on one area of interest, I decided to combine everything we love doing together and put it all in one project. The result — a remote controlled red turtle shell. Here we go!

The Build

We started with some paper mache which gave us a chance to get messy and play with finger paint. Then we chopped out the bottom of the shell and reinforced the base so we could attach the motors. At night, when he was asleep, I took care of the software. The VEX controller was donated by someone who was going to throw it away. Unfortunately, the receiver didn’t have a decoder, so I had to dig around online for a library that could decode the PPM stream from the receiver. That library knocked out three of my PWM pins, so I had to create software PWM signals to control the motors. The rest of the hardware is pretty simple. A dual H-Bridge IC lets us run both motors in forward and reverse, PWM from the Arduino gives us variable speed, and we made a simple 5-volt power regulator. I soldered everything onto perfboard and mounted it in the shell.

The Results

It works, but it could be better. I’d like to make the top of the shell spin independent from the bottom to make it look more like the shells on Mario Cart. Maybe I’ll add some translucent plastic and multi-colored LEDs so the shell color could change from green to red to blue.

Meet Eight of Nine (EON). A sub that takes high-definition 3D video and runs the Voyage operating system (for the record, I wanted to use the DS9 OS, but I couldn’t find any Linux distros with that name).

The project began when I read a Linux Journal article about Cambridge and the Defense Advanced Research Projects Agency’s autonomous submarine competition. For the sake of brevity, I’ll refer to Cambridge and DARPA as “The Collective.”

The Collective assimilated . . . I mean, assembled, a team of 20 undergrads from various engineering schools, so I though a couple friends and I could probably build a submarine too. This sub isn’t autonomous (because we couldn’t afford the sonar), but it does capture 3D video using two GoPros and you control it from anywhere on Earth over the internet.

The Software

I built the control GUI using Python and GTK. It also listens for input from a joystick so you can control the ROV using a game controller. The ROV streams HD video for navigation using gstreamer.

I wrote the main server for the ROV in C, and that listens for communication from the controller or any client that speaks the correct protocol — I started a curses based command-line client :). The protocol is as close to human speech as I could make it. For example, the ROV understand commands such as “dive at 20% power.” The idea was to eventually build voice recognition into the client using CMU Sphinx The server parses that command and passes it off to the appropriate subsystem — motor control, sensors, or lights — and then sends a response to the client about what happened. Finally, I wrote another quick Python script that streams the data from the sensors to the client. The client can then update its gauges appropriately.

The Hardware

All communication between the sub and land happens over Ethernet so the tether was a cat6 cable. The main brain of the sub is a Pico ITX board running Voyage Linux. I wanted to communicate with the sub-systems using USB, so I used one Arduino to control the electronic speed controllers, and a second Arduino to communicate with the sensors and to control the extra lights. To save power, the extra lights are only turned on when more light is needed for filming. — In retrospect, this seems silly; I put three processors on this thing, but to save power we turned off a couple LEDs

Several people questioned my decision to put three processors on the sub, but this design allows me to refactor my hardware the way I’m used to refactoring software; I can completely change the motors and ESCs without affecting the code on the Pico board. I can also swap out the Arduinos for other microprocessors as I learn more about building motor control systems. Plus, I want to do real-time image processing, and, after we can afford sonar, I’d like to add landscape mapping so the ROV can execute autonomous patrol patterns, search patterns, and maybe even a scaled-down version of the Picard Maneuver.

Capturing high-definition 3D video is the ROV’s primary function, so we put 7 motors on it and positioned them so the pilot could move the sub in ways movie-makers might find useful, such as panning, orbiting a subject . . . and doing barrel rolls. So far, we’ve only broken one propeller.

Building a robot is fun, but I was a little disappointed that we weren’t able to make it completely autonomous. Beating The Collective is difficult, even for a sexy bald man.  

The Garden Monitor

Let’s get one thing straight, when I say “Garden Monitor,” I’m not talking about a rain gauge or an anemometer. My garden monitor is really more of a garden guardian. When it’s done it will carry two 125db ultrasonic cannons which should take care of the deer and rabbits who seem to think it’s okay to ignore fences.

To be fair the system does include some more banal sensors, such as a luminosity sensor which records the amount and direction of light. But even those sensors are going to be used for cools stuff like tracking local vampire activity . . . okay, vampire bat activity . . . fine, plain-old regular bat activity. But bats are cool, right? Like bow ties and cowboy hats.

Searching for Aliens

My new house had one of those Direct TV dishes, and since we’re a pure internet-tv house, we don’t have any need for it. Last fall I pulled it off the house and built a motorized itty-bitty radio telescope. I also wrote an Android app that captures my phone’s orientation and transfers that to my home server. This allows me to point my phone at a star, then have the telescope automatically reorient itself on that location.

To be honest, I didn’t finish that one. Once I realized the limitations of the itty-bitty radio telescope, I decided to build a bigger antenna. The rest of the system works, I just need to learn more about radio waves, which is why I got my ham license.

Thermostats Are Boring

A few months ago I heard about the Nest thermostat, and it is a beautiful looking device. Unfortunately, it costs $250. That’s just plain stupid. And, all of the other network-controllable thermostats also cost between $100 and $400. So, out of sheer disgust, I build my own. The code for the thermostat and the Android app to control it are github, when I finish overhauling my Django app, I’ll post that too. I build this for $20. But there’s one catch — The Network.

The Internal Network

I have an extended I²C network running through my attic. I spent a lot of time debating what type of internal network to use. Ethernet seems like the obvious choice, but then each node costs a lot more because they need more hardware. Wireless is good for mobile devices like my garden monitor. It will use a wireless signal in conjunction with three signal-buoys in my attic to maintain exact location data. But, if a node is permanent, like the thermostat, or the signal-buoy, then it needs to be wired. I could just use serial communication, but I didn’t see any benefit to using that over an I²C network. The coolest solution, that I didn’t implement, would be to communicate over the power lines in my house. I’m definitely going to explore this someday, but for now, my I²C network is good enough.

I’ve also built a serial-to-I²C bridge which is also posted on github, to allow my Django app to communicate with the nodes on the network. Right now the bridge can be built for about $20, but most of that expense is the FTDI chip. One of my next goals is to find a good USB library that works on the Atmel chip to see if I can get rid of the FTDI chip which would bring the cost of the bridge down to about $6, which is way better than what some people are charging.