There are a number of 3D printable models in my various posts. Just search for STL. I highly encourage others making and sharing these as well! I would love to see some good accurate 3D models of the classic TOS props, for example. I've been helping some folks on TOS prop CAD modeling projects on the condition that once their projects are over they'll let me release the files here publicly for the community to use with for whatever they want, so you can expect to see some new printable TOS stuff here in the next few months.
3D modeling is tricky and most people just don't take the time to make their models accurate; it's not an inherent limitation of the medium. @EWilliams is a member here who is very careful about CAD modeling and has made some great Trek prop replicas that started out as 3D prints.