This is my take on Laura Kampf's CNC'd driver bit holder (If you haven't seen her video, check it out on YouTube)

I don't have access to a milling machine, went for a different approach. The insert that I have created is 3D printed, and relies on a friction fit to hold the parts rather than magnets.

I added an additional hollow in the middle of the insert. The idea was that this less-accessible compartment could contain less frequently used driver bits, but still keep them together with the others.

In reality, the fit of the insert is a bit too tight to allow the compartment to be easily accessed, but it does still serve a purpose in reducing the amount of filament required to print