Crossbow Trigger. It is designed for a 2x4 cut in half. The drill template includes two holes for 2" nails to hold the 3d printed trigger parts in place, and two holes for pilot holes for a 1" spade bit to bore out holes from the top and bottom for placing the trigger parts into the wood. The 1" hole down from the top goes about 1/2 way through. The 1" hole up from the bottom goes almost all the way, leaving only about 3/16" of wood. The template also has two holes for temporary screws to hold the template to the 2x4 so it doesn't move while you drill.

Place a small screw in front of the trigger to hold a rubber band to hold the trigger forward.