I have some scrap laying aroun and a plasma cutter i was thinking bout making a bunch of circles for gongs. Is there a standard size for distance. I was thinking bout a bunch of four inch amd 6 inch. Im gonna put fence posts at various distances and hang targets. Was thinking boit also making a shooting gallery with targets welded to hinges that would be portable i just dont know what would be the best sizes for them lol so if there is a standard its a good starting point