I'm not a patent attorney, and don't play one on TV (my acting skills preclude acting as anyone but myself), and I DO agree that people shouldn't be able to profit on other people's ideas if the originator's intent is to make money off an idea - but in the wide market, there is a benefit for people to build/sell products based on other people's ideas AS LONG AS IT IS NOT INFRINGING ON THE OTHER PERSON'S INCOME/PROFIT.
For example, not everyone has a 3D printer and/or does not have the want/need/skills (or can afford to buy one), and if someone likes/wants OP's creation, I PERSONALLY think it's fine for someone to print it and sell it to others because OP has no intent to profit from its creation himself. Although I have long considered getting a 3D printer, I'm not going to buy one just because I want to recreate one particular item - but I might be willing to pay someone that is printing them out for sale.
Though one of these days, if I can think of at least one thing to use as an excuse to buy a 3D printer to the wife...
Caveat - I am not interested in THIS particular product, as I have no need/want for such a thing myself.