Here's what I built.......
The black frame is 1/2" ID tubing bent 90 degrees at each end.....
the hangars are 1/4" x 1/2" cold rolled steel
the discs are 2" OD cold rolled steel cut 1/4" thick and welded onto the hangars......
the hangars are just bent in a u shape to go over the frame, and there's a 10-32 threaded hole on the back side, where I insert a cap screw to retain the hangars on the frame.
The silver legs are inserted into the frame, and then I just shove the legs (pointed ends) into the ground.
When hit with a bullet, the discs rotate back and up, thus any ricochet goes into the ground.
I've shot these with up to a .45 ACP bullet, and it's lasted over three years.