Optimised Filament Spool Drawer (Uses ~50% less filament!)

I've always liked the filament spool storage tower, but existing designs waste huge amounts of filament - costing more than it would to buy a storage box. ]
This design reduces the printed material by ~50%. I have minimised the wall thickness and removed the walls which are replaced by any <0.5mm thick sheet material. In the picture I have used Card but literally any cheap/junk material will work!
To attach the drawers to the spool I tend to use wooden BBQ skewers because they're cheap and easily available, model kit sprue arms also work well if you have them lying around.

I've included CAD files so you can edit the drawer's dimensions. Please excuse my slightly dodgy part relations in the SW file, was making this on the fly lol. 

Based on this drawer design: https://www.thingiverse.com/thing:2103466