danger level

• negligible
• moderate
• high
• do not do this

tools

• F. Knife

materials

• A. Paper towel tube
• B. Utility lighter
• C. Hair spray (aerosol)
• D. Duct tape
• E. Ping-pong ball

how-to

1. Use a short piece of duct tape to seal one end of an empty paper towel tube.
2. Cut a hole in the duct tape just large enough for the tip of the utility lighter to fit through.
3. Release a quick spurt of hair spray into the open end of the tube. You will have to experiment to find the best amount — there must be enough oxygen in the tube for combustion. Only aerosol hair sprays will work (the type in a metal canister).
4. Insert the ping-pong ball 1/3 of the way into the tube and then insert the tip of the lighter through the duct tape.
5. Spark the lighter. The piezo igniter will ignite the propellants and the resulting pressure will quickly accelerate the ball out of the tube.

danger level

• negligible
• moderate
• high
• do not do this

tools

• C. Lighter / Matches

materials

• A. Extra Fine Steel Wool
• B. 1/8" x 6' Steel Rope

photos

how-to

1. Dress yourself in pants, a hooded long-sleeve shirt, and safety glasses. There will be sparks flying everywhere so it is vital to protect your skin and face. Also find an open area without anything flammable nearby.
2. Tie a slip knot at the end of the steel rope. Steel rope is necessary because the heat will be intense.
3. Tighten the slip knot around a wad of steel wool.
4. Use a lighter or match to start the wool burning then quickly start swinging the rope around in a circle.
5. Clean up: When the wool is finished sparking the remaining metal will glow red hot for a long time, so have a bucket of water handy to cool it off.

danger level

• negligible
• moderate
• high
• do not do this

tools

• (None)

materials

• A. Neodymium Magnets
• B. Steel Ball Bearings
• C. Plastic Channel/Track

how-to

1. Place the neodymium magnets (available at K&J Magnetics) on the track and place four or five ball bearings in a line touching one side of the magnets.
2. Place one more ball bearing on the opposite side of the magnets, far enough away that it isn’t pulled toward the magnets.
3. When you are ready to fire it, nudge the single ball bearing so it slowing rolls toward the magnets.
4. You can also set several of these up in a chain; each one will fire the next with increasing speed.

danger level

• negligible
• moderate
• high
• do not do this

tools

• D. Needle-Nose Pliers

materials

• A. "AA" Battery
• B. Neodymium Magnet
• C. Copper Wire, 18 Gauge

photos

how-to

1. Place the neodymium magnet on the negative terminal of the battery. The magnet used here was 0.5 inches in diameter and 0.25 inches thick. Anything near that size will work, but normal ceramic magnets are too weak. You can buy neodymium magnets at K&J Magnetics.
2. If your copper wire is insulated you need to remove the insulation. Bend the wire into any shape you want, but be sure it makes good contact with the positive terminal of the battery as well as with the circumference of the magnet. Bending the wire into a pretty yet functional shape takes lots of patience. See the photos for two examples of shapes you can make.
3. Balance the copper wire on top of the battery and make small adjustments in the shape until it spins quickly and easily. The battery will only last a few minutes with the wire on it.

danger level

• negligible
• moderate
• high
• do not do this

tools

• K. Drill
• L. Hand saw
• M. File

materials

• A. Flint igniter (lantern lighter)
• B. 4" PVC cleanout plug
• C. 4" PVC fitting cleanout adapter
• D. 4" PVC coupling
• E. 4" x 24" PVC pipe
• F. 2" x 4" PVC increaser reducer
• G. 2" x 48" PVC pipe
• H. PVC cleaner, primer, & cement
• I. Sack of potatoes
• J. Hair spray (aerosol)

how-to

1. Cut the PVC components to length and clean and prime the joints. Cement components C thru G together.
2. Drill a hole for the lantern lighter in the middle of pipe E and then install the lighter with its included hardware. These lighters are very compact and use flint to produce a strong spark. You can find them in the camping section of large department stores.
3. With the file, sharpen the circumference of pipe G. This makes shoving the potato in easier because the pipe will cut off the excess potato.
4. You’re ready to launch!
   1. i. Find a very large, open area to launch the gun.
   2. ii. Load a potato. Use a stick or rod to plunge it most of the way down the barrel.
   3. iii. Spray the hair spray (make sure it’s flamable) into the fat end of the gun. If you use too little the potato won’t go far; too much and it won’t launch at all because there isn’t enough oxygen in the chamber.
   4. iv. Quickly screw on the plug (part B).
   5. v. Hold the gun at your side, aiming in a safe direction. Give the lighter a quick flick, as if you’re snapping your fingers.

danger level

• negligible
• moderate
• high
• do not do this

tools

• (None)

materials

• A. Bottle of vinegar
• B. Film canister
• C. Plastic bottle cap
• D. Baking soda

how-to

1. Make sure that the bottle cap you have will slide into the film canister. It should slide down freely, but be large enough that it can not flip over sideways while inside the film can.
2. Fill the film canister about 1/4 full with vinegar.
3. Fill the bottle cap with baking soda. Keeping the open end of the cap facing upwards, insert it into the film canister and let it float on the vinegar. The purpose of the bottle cap is to keep the vinegar and baking soda seperate until you’re ready to throw the grenade.
4. Carefully close the film canister so the vinegar doesn’t splash around. (It may be easiest to set it on a flat surface.)
5. Give the grenade a solid toss. As the grenade tumbles, the vinegar will slosh around and mix with the baking soda, quickly creating enough carbon dioxide gas to pop open the film can.

danger level

• negligible
• moderate
• high
• do not do this

tools

• E. Compass
• F. Box Cutter
• G. Straight Edge

materials

• A. 3/8" cardboard, 30" x 40"
• B. 3/8" cardboard, 23.5" x 48"
• C. 3/8" cardboard, 24" x 72"
• D. White Glue

photos

how-to

1. Cut and fold part A, which will form the seat. It is made of multiple 11.5" diameter circles folded over each other to make a strong sitting surface. The narrow strip is folded around the circumferance of all of the circles to hide the edges.
2. Cut and fold part B, which is the weight-bearing element in the stool. It is just a large sheet that is rolled into a tight cylinder. You can make folding easier and more precise by using a straight edge and a blunt instrument to score parallel lines into one side of the cardboard. The cardboard will then fold nicely along these lines.
3. Cut and fold part C, which is mainly decorative. This piece has thin diamonds cut out of it, allowing the middle to be pressed in when it is rolled up. The result is an hour glass shape.
4. Test fit the parts, and then start gluing things together. It will look most impressive if none of the glue is visible.
5. Let the glue dry fully before you sit on the stool. If you have built the stool well it will be quite sturdy, but you should sit fairly still. Tilting or leaning will wear it out quickly.

danger level

• negligible
• moderate
• high
• do not do this

tools

• (None)

materials

• A. Table Salt
• B. Container with water
• C. 9 volt batter

how-to

1. Add several tablespoons of salt [edit: baking soda is a safer choice…read the comments] to the water and stir it until it disolves. This step provides free ions, making a solution which conducts electricity.
2. Place the battery in the solution. You should see tiny bubbles on both of the electrodes. The one that produces bubbles faster is producing hydrogen. The battery will only last a few minutes in the solution.
3. Optionally, you can attach wires or graphite rods to the battery terminals and leave the battery out of the water. Using graphite rods will speed up the process considerably.

danger level

• negligible
• moderate
• high
• do not do this

tools

• D. Coping saw or scroll saw
• E. Sanding block or orbital sander

materials

• A. 1/4" birch plywood, 20" x 16"
• B. Pattern (download .pdf)
• C. Spray paint or clear lacquer

images

how-to

1. Trace your pattern onto the plywood and use a saw to cut out the shape.
2. Use a sanding block (and a lot of elbow grease) or an orbital sander to give each side of the boomerang an airfoil shape. The direction the airfoil faces depends on the hand with which you throw.
3. In the middle of the boomerang blend the two airfoils together. You want the whole surface to be smooth.
4. Give it a final sanding with fine grit paper then apply a thin coat of spray paint or clear lacquer to help protect the boomerang and make it look nice.
5. Now you are ready to throw it. Find a very large, open space (at least a full baseball field). Hold nly the very tip of the boomerang in your throwing hand. You should throw the boomerang nearly vertical but angled outward sligtly. Aim just above the horizon. Throw it hard and overhand like a baseball and flick your wrist as you let go.
6. Go fetch the boomerang. It will take some practice and experimentation before you can get it to come right back to you.

danger level

• negligible
• moderate
• high
• do not do this

tools

• (None)

materials

• A. Small container with water
• B. Cheap cigarette lighter
• C. Matches
• D. Dish soap

how-to

1. Add a few squirts of liquid soap to the dish of water. Gently stir the water until the soap disolves but try not to create bubbles yet.
2. Submerge the lighter in the water and hold down the button that releases the butane. Butane-filled bubbles will slowly begin to accumulate on the surface of the water. To speed things up, you can use a butane refill canister.
3. Using a match, carefully light the bubbles. You should do this outside in a clear area.