The spring has a 0.825 O.D., 0.725 I.D, and 0.05 wire thickness. It's approximately 1.2 inches free length, and 0.300 compressed length. (Spring was selected as it was local.). Century Spring (centuryspring.com) carries a similar spring that looks like it will work nicely: part...
Thumb screw cap is used to level the platform on the Solidoodle 2 from underneath without a tool. The cap fits tightly onto an M4 nut (7 mm wide). No extra materials needed.
Having the issue of filament running into the fan when your Solidoodle extruder is backed into the rear left corner. This should take care of it without needing screws.
First seen here: http://www.thingiverse.com/thing:163784