This is a Gridfinity bin for the popular Optimized Bed Scraper XL by ThreeD-Michael.
It's 2x3x3U, and comfortably* holds the scraper with blade installed, as well as 7 spare blades. Spare blades lift out easily without becoming stuck, there are grooves under the front and rear of the scraper you can press the scraper down on to make it easy to lift out, and all edges are rounded.
* You can fit up to 9 blades in if you put 2 under the front of the scraper, but then you can't press down on the front to lift it out.
The author marked this model as their own original creation.