A person can't print out 3d models without a 3d printer. The models could still be said to be open source. Or taken even further, a person without access to a

A person can't print out 3d models without a 3d printer. The models could still be said to be open source. Or taken even further, a person without access to a hammer would have a very difficult time following blueprints for a house. Open source is really just "given tools and knowledge not specific to this particular case, you can replicate everything we've done". For any sufficiently niche application, "tools and knowledge not specific to this particular case" starts to become an increasingly large hurdle, but I'm not sure I'd go as far as to call open source a myth with regards to hardware.