I’d be quite interested in the Shapeways prep service! Or I’d pay for a tutorial, if you could create one. I have a number of ideas I’d like to try with 3D printing, but haven’t had time yet to figure out how to get my models into stl format, watertight, etc.
Not much of a tutorial required.
1 - Export model in .OBJ format
2 - Import model in MeshLab (free software)
3 - Save file as .STL format
The result will be a corrupted .STL. That is what I repair with the commercial software and almost 2 years of experience I have gained.