Since my old kitchen scale broke I got a replacement from Soehnle, but a different model. So I had to rebuild my original holder that can be found here:
https://www.printables.com/model/587511-kitchen-scale-under-table-mount
You need to print two and mirror the second one. I printed mine in 0.3 and with 10% infill (rectangles). Seems sturdy enough. Use 3.5mm screws for mounting. For convenient mounting there are holes for the screwdriver.
The author marked this model as their own original creation.