The holders can be used separately or connected to the handle. The handle needs two dovetail clips added printed and attached to be used with the holders. See exploded view below.

The 20,30, and 40mm holders only have a slot to connect the handle on one side. If you want them on the other side mirror the model in your slicer. They also have an end cap that can be printed separately and glued in place afterword. The 80mm holder is intended to have a cup placed in it to hold a water.
The author remixed this model.
After using Kinou60s Tool holder for a few years I had the idea to add in a handle and slots to link them together. This way they can be easily taken with you if you’re working at a shared studio space. I also created some different sized pieces.