This is a bit for tightening audio jack nuts that will fit into a 4mm hex (allen) fitting, remixed from ncsonka's original tool. I widened the opening a bit to allow the threaded jack post to pass through for longer jacks, as well as a center pin for stability. On the outside, there are small grooves to indicate the two indents that fit into the nut.

These only last for so long before they get stripped, but they are small and fast to print so you can print off 10 or so and it will only take a few hours. Since they are plastic they won't damage your panel.