Was listening to Steve Anderson's pod cast, and he mentioned a dry fire swinger to get better skills on them. So, i made one.
Pretty easy to make from stuff laying around the shop. Used a piece of 3" wide by about 2 &1/2 ft long piece of 1/8" thick iron i had laying around for the bob weight and to hold the target. (A length of 2x4 board would work too). Drilled a 1/2" hole about 1/4 of the way down. Then found a 3/8 bolt about 3" long, 2 fender washers, 2 nuts and a spacer. Then drilled a 3/8 hole in a piece of scrap plywood. The bolt goes thru the bob weight first, then the spacer then a nut and washer. Then the plywood, washer and last nut. the 2 nuts clamp the bolt to the wood, but leave the spacer and bob weight able to move freely. A piece of scrap wood props up the bob weight and is activated with a pull cord. The target is taped on to the top of the bob weight.
It's not perfect, but is actually usefull and easy to make.