A bow I made as a joke, but wound up being quite powerful, a range of 50-60 feet and being able to go through cardboard.
Step 1: Supplies
First things first, you need 2 hangers, 2 rubber bands (or 1 elastic band from a binder) and some duct tape. Then you tape the two hangers together to form a bow shape. Match up the little rivets in the hanger together to find where to tape.
Step 2: Make a Slot for the Arrow
exactly what it sounds like, take a piece of duct tape, approximately 4 inches long, and take another piece, around 2 inches long, and join them together. Make an arch for the arrow to slip through. Tape it to whichever sided hand you are ( if you are right handed, put it on the right side.)
Step 3: String
Sorry for no pictures, all you do is connect the two ends of the hangers with the rubber bands or with the binder elastic. This is the second one I made, and I gave the first one away with my only elastic, so I just used rubber bands, but it still works fine.
Step 4: Ammo
Here is what I used for ammo
-steel kebab skewer (OW!)
-super thin dowel rods with a little pronged piece of tape at the end( >-----)
but you don't have to do that, just find something sharp that flies straight, and your good to go, as long as it fits into the slot.