Spool holder for mendel90, nophead kit. It is mounted via the two spare holes in the left side.
You need three M4 screws, four M4 nuts, approximately 120mm M4 threaded rod and two 8/22mm ball bearings.
Made for colorFabb 750g spools and you can easy adapt it to another spool size.
The adapter to ColorFabb spools can be downloaded here:
http://www.thingiverse.com/thing:205957 (write to me if the model is not available)