I designed these to fix the socket end of the extension cord to the inside of an infrared sauna where I plug in the headphones. the other end is parked in the other fixture at the outside wall where it can be easily removed and parked again.
Both holders can be printed without supports if oriented properly. The ones shown in the photos were printed with wood filled filament at 0.2mm layer height.
The author hasn't provided the model origin yet.