Summary

Hexagonal shelves made in Autodesk fusion 360. 90mm and 80mm height, I included the 3mf file so you can edit if needed.

Printed on an Ender 3 S1 PRO with PLA, the size is made specifically to fit a 220x220 print bed.

The screw holes aren't threaded, I used drywall screws, 3.5mm diameter screws, the hole is 3.4mm so the screw is snug. The screw head can be a maximum of 8mm.
I tested the mounting screws and it works great, mounted 1x90mm and 2x80mm.

I used 0.2mm print height, 60C print bed, 210C nozzle temp, with a 220C first layer, with great results.
I used 3 perimeters and 5% cubic infill in prusa slicer, and 20% infill for the bottom of the screw holes.

No supports, brim etc needed.

EDIT: working on a solution to cover the screw holes in a clean way