These are tool holders for rulers. They hold the rulers standing straight up, and there are two profiles to choose from:

• "Architect" profile rulers which are shaped like a triangle with circular divots, like those Staedtler scale rulers
• Two "China" profile rulers, which I'm calling that purely because the one I have is only identified by the country of origin. They are rulers with large tabs in the middle of their profile that make them easier to grab.

The "China" profile should also fit any flat ruler that's 30mm wide and 2.40mm deep, or less. If you happen to know what this is actually called, please let me know.

Gridfinity is ©2022 Zach Freedman. Zach recently relicensed to MIT, so that is what this model's license is, too. (If you really want the CC-BY-NC-SA terms, they're irrevocable, but why would you want them!?)

This project was designed in CADQuery; you may find the source files here: https://github.com/kmeisthax/gridfinity-cadquery/blob/master/examples/rulers.py