Maybe I'll switch some bits out with the other 'big' set. See if I can buy another one just for the bits and add the best ones to the 'pen'.

I wish more of 4mm hex bits were double headed. That would make it so much easier to put together a decent EDC screwdriver set. I am also in the proces of making one. I am still waiting to get all the pieces. And at least some of the bits come form a pen screwdriver like yours.