Anet A8 giant spool holder

Here is a large spool holder for the Anet A8 that can accommodate up to 4 filament spools.
It's loosely inspired from https://www.thingiverse.com/thing:1624641 (but designed from scratch, before I realized its scad was available, my bad).
I used Madjestik58 holder for quite some time and loved it but there were two things that bothered me:

* lack of lateral stability (it tends to lean on one side or the other)
* having to screw/unscrew stuffs every time I want to change a spool (which is t