My grandpa used to make them. take 22 shells or shotgun shells, cut away most of the brass on the 22 bout 1/4 left and the plastic on the shotgun shell then glue them to the mouse trap. then he would glue two of those thubm tacks (yeah, two primers, ever hear a double barrel shotgun go off, disharging both barrels?)to the bar that swings. My grandpa would then throw these at me when not expecting it and holy bejeezus do those make some noise when not expecting it. (Outside Use Only) and also be extremely careful when cutting the brass as the shell may heat up too much thus exploding in your fingers(OW!). Give some info. Yay or ney