This is a Gridfinity drill bit holder which can hold 5 drill bits in a 3x1 (2U height so they can stack) space. The .stl file is set up to hold five bits:
Includes a small drop at the end of the drill bit so you can push down and lever it out of the space.
This works for one of my sets of drill bits. However, I realise everyone has different bits. So I've fully parameterised this, allowing you to set diameter and length of each drill bit, plus some other options.
The author marked this model as their own original creation.