Well ... uhm ... I just had published my Mini Bit Driver Keychain when I got another idea: What if I double the bit driver?
I just had to do it: The Mini Double Bit Driver for carrying two of your beloved bits!

Print the caps in PLA with a layer height of 0.2mm, 3 walls, 5 tops, 4 bottoms and 15% infill. Support is not necessary. I recommend using a brim, that will improve the bed adhesion.
The driver itself needs support as shown in the picture or in the 3mf file (for Ocra or Bambu). The rest of the settings are the same as for the caps.
The optional gaskets should be printed in TPU. Use a smaller layer height (e.g. 0.12mm), no brim, 2 walls, 3 tops & bottoms, no infill and no support.

For assembly just add two standard bits. I testet serveral bits and they all had a tight fit. If necessary you can add two Ø5x2mm magnets - there are a holes for them inside the driver.
Screw the caps on the driver. The threads are similar to M12 but extra tight so they do not come open in your pocket. The gaskets are optional and can help to prevent unintentional opening of the threads. If needed just press the gaskets over the threads to the little grooves at the bottom end of the threads.

Disclaimer:This work by blecheimer is licensed under CC BY-NC-SA 4.0.You are not allowed to copy this model to other 3D printing websites without my permission.