EDIT: Added three new tray options, one free-standing tray and two Gridfinity-compatible trays. Details below. A selection of storage trays, to keep your FDMecha Hex Terrain tiles organized:

• The stacking tray holds roughly 100 tiles (give or take a few, depending on the exact tiles), and stacks in an interlocking fashion to securely shelve and carry multiple trays at once.
• The refill insert tray holds slightly fewer tiles than the stacking tray and doesn't stack, but does print in a single piece with no assembly required and fits neatly in the older style of Bambu Lab filament refill boxes (and presumably other filament boxes of similar size and construction, though that hasn't been tested at time of writing.)
• The free-standing tray uses a bit more filament than the multi-part stacking tray, but prints as a single piece, holds about the same ~100 tiles, is also stackable (though doesn't interlock quite as securely) and has textured side panels for ease of handling. (For anyone who's bought into the Modi Boxi storage ecosystem, it also exactly fits into a Level 2 Large boxi.)
• The 3x5 and 5x5 Gridfinity trays are similar to the free-standing tray, but with Gridfinity-compatible bases and stacking lips. (For reference, they're both 9u tall in standard Gridfinity units.)

Instructions:

• For the stacking tray, print 1 base, 2 endcaps and 2 top rails; parts should press-fit together with a little encouragement. PET-G recommended.
• For the insert, free-standing and Gridfinity trays, just print in PLA or PET-G.