There's some hooks out there that are designed for the hook hole that you get in the end of straightedges, but I wanted something that's more of a slot, so this idea popped out of my head.
Basically, there's two pieces to this, you print both of them (at the same time, or you can split them up) and the one with a solid bottom is designed to be below and then the one without a bottom is designed to prevent the object from falling out.
I'm saying it's a ruler holder because that's what I was trying to store but it will probably work for other long not-especially-heavy rectangular objects just as well. Presumably you could print a second bottomless version for more support, etc. If it's awesome for something not-ruler-like, I'd love to see you post makes!
This requires you to install the BOSL2 library and the OpenSCAD library for HSW attachments to work. There's also a mesh, but you don't want the mesh, you want the OpenSCAD version so you can crank out whatever dimensions you desire. The default setting is what worked for my assortment of rulers.
It's designed to print without supports and go straight into the honeycomb without needing any extra inserts.
The geometry for HSW is generally designed for PETG. I printed mine with Prusament black PETG on a 0.4mm nozzle.
The author remixed this model.
The OpenSCAD library for HSW attachments module generates the inserts, this is part of the HSW system.