Now THAT is a very hard thing to do, and also an area of interest for me and my friends. Check out a guy named Joe Barnard at BPS space on YouTube if you want to see exactly that in action. Requires a wicked amount of electronics and coding experience thought. To make it dangerous you also need to know how to mix explosives which is already a common watch item anyway. Restricting printers won’t fix that though because anyone smart enough to do what you are saying can make a printer from scratch