Prusa Mendel i2 frame mounted spool holder

I designed this spool holder to get the last meters of filament (3 mm and curly) from the spool. Up till now I have used this spool holder: http://www.thingiverse.com/thing:29526. The problems occurs when the printer is chewing its way through the last meters of filament. For that, the way from the spool to the print head should be as short and straight as possible. So I started looking for a frame mounted holder and found this design: http://www.thingiverse.com/thing:32320. I printed the mounts, but they did not fit my Prusa Mendel i2. So I designed my own spool holder inspired by both of the designs mentioned. Features of the spool holder:

• mounted on top of the printer;
• quickly change a spool;
• can be added without disassembling the printer;
• uses bearings.