I printed at 0.28mm (with 3 walls) on my Ender 3 Pro, took around 10hrs. Both parts were printed one at a time over the course of 1 print.

Should be good for small screws with the holder in if you take the part holder out should be helpful for a wide array of things.

NO SUPPORTS needed anywhere

EDIT

Revision two features an improved to the way that the removable tray sits in the bigger tray, while this design has a small (1.4mm) overhang it should result in a better fit for the removable tray. NO SUPPORTS needed.