I built one last weekend, took about 4 hrs if you don't count paint. I just used regular steel so I doubt it would stand up long to center fire rounds, but you can shoot 22 at it all day. If you do decide to build one I suggest you design it so you can adjust the angle that it tips forward as you can tweak how easily the targets swing. Too much angle and 22 won't kick them around, not enough and they swing around and bounce and don't seat properly on the other side.. I found that you may need to adjust it with the distance you intend to shoot it from.. It's loads of fun though