I ordered a quad upgrade and the spool holder took extra spaces. I designed this so that these spool holders are stacked on top of each other to save space. I have yet to test the printed parts nor the strength of the acrylic frame. I am concerned that it might break but it also should able to withstand about 2.5kg weight.

Check this out for easy filament access https://www.thingiverse.com/thing:2512730

Print 4 middles and 8 corners to have one of them stacked on top of the previous.

Use any 20mm pipe and cut them to at least 20cm x 6 pieces of them.

On fitting the printed parts to the pipe, I would recommend fitting the printed parts to the spool holder first then gently knock them together down as not to break the spool holders