Flat spool holder and filament guide for Wanhao Di3

Wanted to bring the filament guide into a more central position, required lengthening to bring it forward to prevent filament bending/catching on the bottom edge of the spool. Added a cable tie as the guide arm doesn't sit flat when bolts are tightened - this was also an issue with the original but it doesn't affect the rotation or movement of the spool whether you tie it down or not. Many thanks to original designer - I only remixed and remade this because I managed to knacker the original I ha