Well i can say this:
The trays should be plastic and have a lid, people would download a decal for the set up ( either global, 42.2, 41, whatever which files will be made available).
The dividers should be no more than 6 sections ( land x2, Naval x2, Air, tokens) The words printed in the plastic: Infantry and Mech, Tanks-Artillery, Battleships- Carriers, Cruisers-Destroyers-Subs-Transports, Air Units, National Tokens
The tray should be flat and wide, so it fits in the OOB box ( total trays will fit unstacked inside box so consider the surface area)
Thinking white would be a good color. People could paint the script inside the trays which are raised lettering. The lid must be fully retractable and flipping it all the way does not imbalance the tray. The clips or whatever system is used to close must be non-break proof…using plastic that wont get brittle over time.
If you go with wood, then the lid could just slide out, like a flat cigar box