.stl is for 3D printing.
Native Solidworks, native ProE, .stp and .igs for machining. Although that gets converted to cam data depending on what type of mill used.
3D printing is not ready for prime time. Maybe in 5-10 years.
This.
OP: I was in a 3D printing workshop from my uni last month, I'll post the link to my project once they put it online. I specifically asked the industry people what use current gen 3D printing has in the restoration world, and they confirmed the suspisions we had on this forum in an earlier thread that you can't really replicate the structure of the materials you try to reproduce, meaning you can't print reliable replacements yet.