PB Swiss makes an interesting bicycle multitool that uses a 5mm L-shape hex wrench as a handle and an adapter to fit regular 1/4" hex bits. I don't want the tire irons that come with the tool, but I need it to hold more bits, so because they sell the adapter by itself, I made a bit holder for the adapter, a 5mm hex wrench, and fourteen 1/4" bits.

I actually have two designs- this full form one with the bits enclosed on all six sides, and a skeleton version where one of the sides is open. Bits are easier to remove from the skeleton version, but they can also fall out more easily, and it flexes side to side more. I tried to be a bit too fancy in trying to form leaf springs to help hold the bits in for the full form version. I suspect it's mostly the little bumps in the hex holes that are catching the grooves in the bits and holding them in. If you can't pull the bits out, there are holes on the bottom so the hex key can push them out.

I have the model tuned to my 3D printer that makes holes smaller than the model shows, so I have included the Fusion 360 model file for this part in case anyone wants to modify it. The problem is there is a lot of cruft from previous iterations, so it may be a bit difficult to follow what I tried doing, though the user defined parameters probably help a bit. But it is probably easier to just scale the model X and Y axes up or down in your slicer to get a good fit.