Loading aid for the MMU3 buffer segment R4

Similarly to remix from @ticat_105850, this remix significantly simplifies the insertion of the filament into the buffer (but uses newer R4 segments).

Simply insert the ribbon fully into the cassette, push filament all the way into the MMU unit, and then pull the ribbon. Done. No need to remove the cassettes from the buffer.

Part list:

• 5x Cassette Segment R4 side A
• 5x Cassette Segment R4 side B
• 5x Ribbon from Ticat remix
• Remaining parts from MMU3 cassettes
  (5x wheels with ball bearings and shafts, 25x M3x6 screws, 15x M3 nuts, 10x collets)

You may also want to consider Cassette Compatible Buffer if you want to have it contained within Prusa Enclosure.

Redesigned MMU3 R4 buffer segments with ribbon paths similar to model by ticat.