He also couldn't build the bean popper without permission from whoever, if anyone, owns the patent on the regular popper.

I read that if someone owns a patent on a 3-legged chair, and you invent the 4-legged chair, you can get a patent on the 4-legged chair but can't build it without permission from the guy that invented the 3-legged chair because he has a patent on chairs with 3 legs. But that guy couldn't build your 4-legged chair either without your permission.