This is the latest iteration of a ECD pocket screwdriver I've been using for around 5 years. It holds 14 precision (4mm) bits inside the handle, the bottom cap doubles as a magnetic screw tray, and is compatible with double-sided bits (recommended). The magnets in the tip both make the bit exceptionally magnetic, but also reinforces the plastic. The bit holders are magnetic both to retain the bits, but also so you can split them in two and stick them to ferrous surfaces.

The orientation of some of the magnets is very important. The three magnets in the tip need to have the same pole facing in, twords the center, or the inserted bit won't be as magnetic as it could be. The easy way to accomplish this is to half insert the magnets, then make sure you get the polarity correct of each successive magnet. Also, the magnets in the bit holders need to be opposite polarity so their flat sides are attracted to each other.

The bit holders are glued together. You can use super glue, but I have had better luck with weld-on 16, at least for PETG.

I would recommend that you print this out of PETG or PC. Nylon might be too flexible, and do not use CF/GF filaments because they are too brittle. The handle I printed out of PA-CF broke the first time I dropped it. I recommend printing this with extra walls and concentric top and bottom layers. I also added a mild fuzzy skin for aesthetic reasons, but only painted on the exterior.

The parts you need are:

A precision screwdriver set for the bits. I used this one because it was cheap and had double sided bits. https://www.amazon.com/gp/aw/d/B0D1GFGC71

20x6x2 magnets - x3

12x3 magnets - x3

glue like super glue or weld-on 16

Later I may draw up and release a varient that only uses 10x3mm magnets, so you only have to buy one size of magnets. My original design used 10x2mm magnets because that's what I had on hand, and it worked pretty well. I just like the triple magnet design better, and I had exactly three left over from a previous project.

I keep this organized in my pocket with this inhailer cover, but every brand of inhailer is a little different, so it may not work with yours. 

I'm licensing this public domain, enjoy.