This is a Gridfinity holder for step drill bits like these: https://amzn.to/49THBgP

It is half pitch, which means the squares in the base are half size so you can place it in more positions but it's completely compatible with standard Gridfinity.

The drill bits are completely under the top so this is completely stackable.

It is 1.5 by 2.5 Gridfinity units on the base, and 5 units high (38.8mm).

I recommend you use the 3mf file, but I'm also including the stl just in case. The Fusion f3d file is also included and hopefully it's easy enough to edit if your drill bits are a bit different.