I bought this tool off amazon and it works well, but there is no storage for the Bits or the wrenches to make adjustments. I found a couple different versions of what I wanted and combined them into this addon for the top of the tool. The threads are tight so the first time you thread on the inserts it will be tough, but after they should get easier to thread on and off.

I printed in PLA. That has worked fine for this. The hot part of the iron doesn't get close enough to cause any melting hazards.