Stackable Filament Holder with fully printable parts

Here's my #FilamentChallenge. I wanted this to be print-and-play so even the bearings in the tube are 3D printed in place. Use the mid-beams to stack holders laterally and the puzzle-piece base allows fore and aft stacking (the multiple guide holes allow for guided back row spools). I'll add clips to pinch spool filaments that aren't being used.

This is one of my first designs with AutoDesk Inventor so I'd love advice or constructive criticism. Even with the base separated in half, the