This is a simple gridfinity bin to fit a 12" ruler. There are two versions, one that is .5u wide that has one slot for a ruler, and another that is 1u wide that has two slots.
I also provided the f3d file for easy editing.
Dimensions for the slot: 320.5mm L x 5.25mm W x 14.1mm H
Originally designed to fit the Alumicolor 12" Desk Ruler (like here: https://www.amazon.com/dp/B00290HBFG?psc=1&ref=ppx_yo2ov_dt_b_product_details)
Fits in the Ikea Alex top drawer (the narrow ones).