Part of Ed's Skadis Shop Stuff collection, a set of Skadis holders and gizmos intended to have pleasant affordances and share common visual design elements. Fits the Skadis Universal Hook by CSD_Salzburg. Uses the Slide-Down Universal Hook Catch for Skadis by yours truly.
This guy is designed to hold simple, flat, relatively narrow, straight up-and-down tools (you know - like a ruler?) with a nice little bit of help to positively drop them into place and pull them free.
The red aluminum company here in the US makes the canonical inspiration for the 6" Precision Pocket Ruler (Amazon / Temu, affiliate links, Jeffy B, etc) included as a STL, but you can get these from all sorts of places. (As an aside: I think making these longer than about 6"/160mm is probably not particularly useful.)
The holder we've got here, though, is parameterized. It shrinks down to hold a 12mm ruler or gets as wide as you probably practically want, or as tall. The world's your oyster.
Please note: all my Printables models that are not a remix of others' work are licensed CC-BY-NC-SA. Commercial usage is available upon request; please reach out via email.
The author marked this model as their own original creation.