I loved the idea behind Laura Kampf's Zippo bit safe, but only including four bits seemed like a huge waste. I also use precision screwdrivers much more often than these full-sized tool bits, so I decided to design a version around them. This set includes a precision screwdriver handle, which doubles as an adapter to a full-size (1/4" hex) bit. The insert to hold the bits is 3D printed, as well as a driver end with a rotating head (using a 623 bearing) that allows it to be used like the precision screwdrivers that typically come with these sets. The insert holds the main driver/adapter piece, plus 12 of these smaller precision driver bits. In place of one of these 12 bits, you can include an extender as shown, but you will have to cut it down a little to fit inside the Zippo shell. Earlier versions used a friction closure like Laura Kampf's version, but I couldn't find a way to make that work in this version without wasting the very limited space or making the bits hard to remove. Instead, I cut a length of a 1/4" wide pocket tape measure to use as a spring to hold the lid shut.