Solidoodle 3 Spool Holder

I rebuilt a nice Solidoodle 3 printer frame for use with PLA plastic. Sadly, my filament delivery system for the ABS-only Solidoodle 4s that I use didn't work so well with the PLA filament I'm using on the SD3. Thus, I had to design a limited space spool holder for the SD3's rear edge.

This may be compatible with the Solidoodle 2 and/or 4. However, I do not have an SD2 to measure, and I'm unwilling to remove the lid on one of my SD4s to measure whether or not this is true.