I designed this caddy to hold the lego coasters that I printed (shared link below to the coaster). I made the inside dimension 3.9" square. The design is in Onshape and its titled coaster caddy so you can either go there and rescale it or try to scale it in your favorite slicer. In order to keep it simple the bottom is flat and I just got those clear gel dots and stuck 4 of them on there to get it off the table. You will want to orient that so that the bottom sits on the build plate.

https://www.thingiverse.com/thing:6860218

Anycubic

Kobra 3

Yes

No

.2

20