This is a projectile launcher that I made with my dad (yes, I did say dad, I'm only 13). If you work on it straight through, it will probably only take two hours at most. A friend and I started making these with a straw, tape, and a rubber band. Then we got to legos, and finally a more permanent version. this will shoot barbecue skewers at high speeds, but I'm not really sure about how far in feet it goes. You'll have to try it out =)
P.S. You might want to add flights ( like feathers on an arrow) so the skewer will fly straight. If it flies straight and true, this is a killing machine, so be careful (and send me a pic of how you did it).
Step 1: Materials
plank of wood
2 copper pipe-fasteners
2 cup hooks
2 eye screws
1 long rubber band
a lot of barbeque skewers
Step 2: The Barrel
I put 2 cup hooks in right on the edge of the base, then 2 eye screws in 13.5 centimeters behind those. The cup hooks are about 5 cm apart. Then, cut about 19.6 cm of PVC. Size doesn't matter, but the skinnier the better. Clamp the PVC down using 2 fasteners. You might find it necessary to take up some space in front so the barrel doesn't wiggle.
Step 3: The Firing Mechanism
Get a large rubberband. place it so the sides are about 1" apart and wrape tape around the middle to make the catch. Stretch the rubberband through the eyes into the cup hooks. Now head off to the firing range!
Step 4: Firing
to shoot, insert a skewer into the front end of the barrel so the back of it hits the catch. Pinch the tape around the skewer, pull back, aim, and let go. I shouldn't have to tell you to be careful, because even if there aren't any flights, it can still pierce skin and mortally wound.