There is nothing that prevents one from making opensource laser printer. Except the fact that the whole mechanism is decidedly non-trivial to get right. You get

There is nothing that prevents one from making opensource laser printer. Except the fact that the whole mechanism is decidedly non-trivial to get right. You get precision mechanics, high voltage, large resistive heating element and multimegabit serial datastreams that have to be phase locked to mechanical movement in one little box that can be bought off the shelf for <100USD. For that matter many "printer manufacturers" actually buy the whole print engine as a module from somebody else as there is not much to be gained by designing and manufacturing it in-house.