After using my original wire twister design (https://www.youmagine.com/designs/electrical-wire-twister) for a while, I decided that having to use a screwdriver to clamp the wires was a bit too much trouble, and I was always afraid I would stab myself with it. I decided to make a wire twister that didn't need a screwdriver to secure the wires and this is what I came up with. It is so much faster and easier to use, I don't know why I didn't think of it sooner.

There are two main parts- a spinning clamp that goes into your electric drill/screwdriver and a fixed clamp that attaches to a table or shelf.

The key to making this design screwdriver-hand-stabbing-free is to use Wago 221 lever nuts to hold the wires. They will accommodate 24-12 gauge wires and clamp securely without any tools- just lift the lever, insert the wire, and snap the lever down. If you have a bench vise you can just hold a Wago lever nut (or even just the wires) in it and forego printing the fixed clamp.

The clamps fit the Wagos tightly but, depending on your printer settings, they may pop out of the printed clamps when you twist thick wires unless you add a drop of glue to the bottoms of the Wagos before you insert them into the clamps.

Video here:

The photo shows the wire twister in "storage mode" with a piece of wire connecting the two pieces so they don't get lost or separated in your tool box.