@JordiGH probably like $4, but i can check that later too, if it's less than an ounce, which it most likely will be i can just use a forever stamp and a normal envelope.
I've sent 3d printed stuff via a normal envelope before, even with magnets attached, and they've gotten there fine. Can't say the same thing about the envelope, but maybe wrapping it in a sheet of paper will help? Whatever, should be fine ;)