I'm using sketchup, and saving my models as .dae files. I've uploaded two alright, but two other ones I've tried keep giving me the message "The fileformat of your object cannot be processed by our software. Please investigate the problem and try again."
So my process goes like this:
1. Export as DAE from Sketchup
2. Open DAE in Meshlab
3. Check for manifold problems by going to "Filters>Cleaning and Repairing>Remove non-manifold faces"
4. Go to "Save as..." and choose .stl, and make sure to actually add ".stl" onto the file name, otherwise it might save your .dae as a .dae.
5. Upload to shapeways and choose "Inches" as unit of measurement (I use millimeters in sketchup, but for some reason I have to choose "inches" when uploading for proper scale)
Thanks. Yeah I did try that. Meshlab just would not solve all the problems; filling holes for example. I simple four sided column with 1/2" "indents" on each corner would give me holes on each edge!! Ridiculous....
On another thread I have been told that Sketchunation.com has some scripts that let you export to STL directly from Sketchup... although if there are errors in the model that wouldn't work either, would it?