Sometimes you have to start a nut on a pot that's upside-down and recessed into a hole that's too small to use your fingers or even needle nose pliers. The Aux Out pot on a vintage Wurlitzer 200A electric piano is one such example. In the past, I have done it by stacking 5 or 6 nuts in a ½" nut driver to carefully thread on only the topmost nut in the stack. That works great if you can find 5 or 6 extra nuts. This tool eliminates the nut-stacking and allows you to thread one nut onto the barrel. Then you can follow up with a nut driver if you want it tighter. Fits standard ½"nuts. You can scale it to fit other size nuts.

Note that all of the print files are for fully updated MINI+ and Mk4 printers with input shaping firmware. Of course it is a very basic model which you can slice yourself for any printer.