Hexy Desk Riser - Uses Ikea BURHULT Shelf

Overkill on material use? Certainly.
Hexes? You got em.
More hexes because you want to use honeycomb infill? Hell yeah.

Uses the BURHULT Shelf from Ikea - white59x20 cm

I've uploaded the original as seen in the photo - but the tolerances are very tight to prevent racking (I learnt the term just now from kap_bid on Reddit).

Rather than throwing out a modified but untested version, instead, consider scaling the print up a tiny amount if you're worried about tolerances.