There's plans for an 7.62 Tokarev pistol based on the AK style action that have been floating around the internet since forever. No drill press or router required. Just a drill, file and some misc hand tools. The AK style action lends itself well to that kind of ghetto fabrication because it's a stamped receiver and machining tolerances can be described as "optional"
It's legal to build your own guns but people who disseminate info for how to do so have got in all kinds of legal trouble. Defense Distributed, codeisfreespeech.com, etc
3d printing isn't that sophisticated considering you can build a working AR with off the shelf parts, a drill press, and a hand router.