this is a Remix from jarkman's tray design for Skadis. I upsized it to 10x10cm and added a 3rd T-Clip for strength.
To mount the holder to your IKEA SKADIS, the T-clip is required:
https://www.printables.com/de/model/256896-skadis-t-clip-system
The author remixed this model.
upsized and 3rd T-clip added