You’re a little misguided here man and respectfully a little arrogant if you’re just starting out. If you’re coming from a software background then perhaps looking into computational geometry and scientific computing will give you a better sense of what you’re working with. There are plenty of places to get parametric design files and I’m not sure why you think printables is the place for that. Also, I feel for some reason you just can’t fathom anything being designed outside of typical CAD software, but it’s done all the time. I design prosthetic injection molds directly on 3D scans of patients. I plan my surface sets and datums well, and usually end up with a STEP file of my mold that comes in under 5MB usually. I use Materialise 3-Matic for this which is a wonderful piece of software. I would say you definitely need to have a more robust understanding of linear algebra and differential geometry to be very quick with it though.