You can 3D print, forge, smith, or machine your guns for your own use all day, everyday. No serial numbers. No permits. No license. You can't sell as then it becomes a regulated business by the BATF. Now you better have some experience and run your own quality checks or it becomes an experiment in Darwinism.
Very good question. Depends largely on who the non-pilot is, how the communication links are, and circumstances. I had a chance to spend about 2 hours in a 757 simulator from a friend at United. After having fun for about 20 mins, I asked the sim trainer to spend the rest of the time showing me how to fly in a crisis situation. My reason being, survival. I learned a bit about key instruments, key alarms, radio operations, and flight computer programming. I think is it not impossible to land. Very difficult, but not impossible. I am a physician, and have no doubt that if a pilot was to spend a few hours in an operating room, I could get them to close. Not pretty, not replacing a surgeon, but in survival mode could have a win.