This is holder for power extension cord from Lidl. But this outlet has quite common dimensions:
Height: 38.5 mm
Width: 54mm
Diameter of cord holder: 28mm
Due to it's two piece design, lenght of outlet doesn't matter.
To mount it on a wall you need only two flathead self-cutting screws.
Printing instructions:
Printed with Prusament PETG in 0.25 resolution and it is just fine (in draft it is quick print, all is done under 2 hours).
The author hasn't provided the model origin yet.