This is a very basic rack system specifically for storing the modular hexes from Tabletop-Modellbau (https://www.tabletop-modellbau.de/en). You could use it for other things, the original intention is the TM hexes.

I couldn't find anything that worked to my satisfaction so I put together a very basic rack system myself. There are six sizes of rack to accommodate the different heights of the hexes and a postless file for putting at the top of a rack.