Here is a closeup view of the clip parts. I call it a clip for lack of a better name. I cut them from a 3/4 inch piece of maple using a scroll saw. One could use a band saw or even a coping saw. The interior cut could be made with a drill and a pocket knife.
Any woodworking hobbyist can build this simple device. There are many ways to cut it out. A drill and a pocket knife would be the simplest way. If you have a need for the device and no way to build it I will cut one and send it to you. I never take money.
As you can see from my pictures the part of the cable that the photographer would normally hold between the two fingers is allowed to ride loosely in the bottom clip. There is no rigid fastener. This prevents any sort of binding by allowing the shutter release to swivel. The cable release rocks several degrees in the clip when the release is pressed. If the outer sheath were held in a ridgid position a side pressure would appear, interfering with smooth operation. I have had no problem with the cable falling out of the clip.
I have never made any real drawings of the clip parts because I did not think it needed. The device is about 1" wide and near 2 1/2" long. All of my releases are a little bit different. I add little improvements as called for. If you try you can improve on my release. I would like that!
If you want another closeup view click here. These parts have just been cut and not sanded or fitted.