Prusa i3 spool holder with filament guides

MK3/The filament guides can be opened for the filament to be inserted without unloading from the hotend (I find that useful). I had tried inserting small pieces of teflon tube in this design (to be openable from the side) but I've given up after failed attempts (too tiny), because even without teflon there is no noticeable friction added.

Required:

1x M4x20
1x M4 hex nut
2x M3x8 (or M3x10)
2x M3 hex nut

I recommend using PETG because of better inter layer bonding compared to PLA, just make sure to print with high enough temperature. Also use many perimeters to make it stronger.

I don't know if it's compatible with MK3/MK4 (I'm using it on a MK2).