Those parts are made to improve printing quality of your Ultimaker 2. You can print flawlessly 50% faster! Also the spool holder feature a self-retain...ing system, making it more cool!
Instructions:
- Wall thickness, 1.2mm minimum. Otherwise it might break if loaded with big spool.
- Don't print in PLA . It has no "spring". Use ABS or PET. I use Colorfabb XT.
- The Spool Holder fixture and Filament Guide fixture need supports when printing.