You could get the tools,buy the sheet metal,make an atx back template,cut,bore,then finish the openings(de-burr,take the edges off).way too much work when a new case can be had for $60. I would use a drill press, a dremmel tool,prob a 3/8 commer. variable handheld drill,drill index,center punches,rat tail files,sheet metal crimpers(to return the sides,top and bottom of the back for attachment to frame. Spend way too much time to end up with a workable,backplate that I could prob. cut free from an old case for a couple of bucks. Sounds like a fun project though. Please post a pic of it.