Here are measurements and a materials list the way I build them. Obviously, you can substitute other materials.
2 pieces pvc 1 1/4" outside, 32" long
4 pieces pvc 1 1/4" outside, 48" long
6 90 degree elbows
2 pieces 1 x 4 western cedar 34 1/2" long
2 3/8" bolts 3 1/2" long
2 nuts and washers
4 sheet metal screws to attach boards
4 tent stakes like Walmart sells
1 corrugated cardboard 26" x 30"
6 screws and washers to hold cardboard on wood
The bottom cross piece of pvc has 2 holes drilled through, and the two elbows on the ends of the legs have holes drilled through for the 4 tent stakes to go through.
The combination of the legs and the cross piece allow you to level in virtually any terrain
This setup is very stable in windy conditions.
I use roofing nails or tape to attach my targets, and also use the Caldwell peel & stick types.