This is a derivative of JoeyC's awesome thing:34852. Much of this is his wording + my respectful commentary. All I did was add a cavity in the handle to store my extra bits. I also added an end cap.
Fully configurable magnetic handle for 1/4" driver bits.
(JoeyC intended it for driver bits. From the picture you can see I'm using mine for drill bits, which I use to clean out and dress up small holes in my printing.)
JoeyC couldn't find a handle he liked for some metric driver bits, so he designed this awesome one.
I like the compound curves in the handle. He clearly paid attention to ergonomics. The handle feels very comfortable in the hand when pressing into your work with the tool.
It uses an 8mm magnet to hold the bits in place, and is easy to change to suit your preferences.