I havn't made one in a loooong time, but I used to make cardboard box traps. Just get a cardboard box 12" or bigger on all sides (16" is best). Cut a piece of carpet to fit inside the box and reach top to bottom. Tack the carpet to a 1/2" dowel and either thread the pole through holes in the side of the box or just set the pole on the edge. Tape a target to the front, close up the top of the box and have at it. Depending on the type of carpet used, and how many layers, even a low velocity .22 can't escape. Just make sure the fuzzy part of the carpet points towards the front.