The final instructions (as sent to press) are here:
This being open hardware (CERN OHL 1.1), here are the files:
These are also on Thingiverse: http://www.thingiverse.com/thing:116610
And here is a more 3D-printable version by Brad Dudenhoffer:
Order a 3D print on Shapeways here: https://www.shapeways.com/model/976427/public-lab-smartphone-spectrometer.html
Sketchup model: smartphone-spec-overview.skp
Here's a list of other adhesives and tape strips which may be helpful in assembling and mounting the spectrometer. Some may be shipped in the kits:
Photos of the assembly process.