After the excitement over the mobile (Android) spectrometer prototype, my nice 3d model printed terribly at Shapeways. It was also covered in a kind of black powder rather than being actually printed in black. I'm going back to PVC (see below) for now but would like to try to improve my 3d printing as well if folks have suggestions.
In the meantime, I cut up the 3d printed parts and reassembled/glued them back together as a workable device which leaves your fingers a little sooty.
Update: Here's a link to the Sketchup file I used: https://publiclab.org/sites/default/files/plots-spectrometer.skp