Inspired by some laser cut projects on Thingverse I made this crossbow for my son. It uses a rubber band and has the gun lock built into the handle. It will shoot a sucker dart across the kitchen and stick it to the microwave with a satisfying smack.
Cut from 3/16 and 1/16\" sheet. I used cheap plywood from the home center and cut it out on the scroll saw, but it needs a laser cutter to make it smell right.
Cut out the parts.
Insert tab A into Slot B... Etc.
The prototype didn't use any glue or fasteners except for some toothpicks to connect the linkage from the trigger to the rubber band catch.