UPDATE I've added a new rev. B: check below for improvements.

I have searched and tested many spool holders, but none actually fit my requirements so I made my own using designs I've found here as a reference, in particular:

• this design from ali55
• this deisgn made by steveyum

This spool holder is meant to stand on top of an `8mm` thick frame, like the Geeetech I3 Pro B acrylic frame, and is capable to withstand the weight of up to `3` 1Kg spools (around `3.6Kg` total weight). It is intended to optimize the volumetric impact of the printer, not extending too much vertically while remaining within the printer horizontal projection area. The curved lines of the holder allow some flex under weight, but they also ensure no interference with the LCD and its buzzer. Used with the standard 1Kg spools (`~203mm` outer diameter) no filament guide is required because the standard direct drive extruder is constantly visible in a straight line from any of the spools.

When mounting, ensure the brackets curved faces are directed toward the LCD screen while the bracket flat touches the external part of the frame, at least on the left side of the printer: this allows access to the SD card slot.

UPDATE In the newer rev. B I've reduced the curvature to ease SD card slot access, while also widen up the bracket to use the LCD screen as structural constraint. In addition, in order to simplify spool change, I've changed the shape of the PVC pipe lock so that now the pipe can be snapped in place without having to remove the bracketsç trust me, that makes a huge difference!

It is meant to be used with a `20mm` PVC pipe and uses spool adapters to center the spool on the pipe, depending on the spool hole:

• 35-70mm designed by me for greatest reliability (no slipping), but requires a decent amount of filament
• 57mm, can get slippy after a while
• 53mm, can get slippy after a while
• parametric, uses some filament, but not much, can get slippy after a while
• parametric, very light on filament, can get slippy after a while