Don't have to prove it. I started making my own race parts in 1977 after hours at the Volkswagen shop I worked at, with the blessing of the owners. Southwest Import Rebuilders. If you do your math, that would make me 17 years old. I lied on the job app about my age. I didn't live with mommy either. So I'm not exactly new to the idea of making your own parts, or doing things on your own.
And today, I'll make stuff I need if I have to. Usually if it's someone else's design, I'll buy it from them, to show my support for them. Like SuperDiesel and other inventors. Of course I'd never sell someone else's design; it would be publically advertising that I'm not capable of free thought or creativity.
Hopefully someday you come up with an original idea, and make a part of your own design, and someone will start copying it and posting all over the internet that you're a rip-off, since they can make it cheaper.
Then perhaps you will figure out what the "difference" is.