Stronger Radiator Towel Hook v2 (with magnet)

Update:

I have added new version (prototype) with two bumps that should snap onto the top rooster ribs. See file StrongHookClick

It works with my no name brand radiators. I don't expect that all radiators are made with the same dimensions but maybe we are lucky. It installs with very noticeable click and it's somewhat more difficult to remove - but that was rather the point. If it works for you than magnet is not mandatory, I guess.

I have not removed the old version as some may find it still useful.I have redesigned my other model https://www.printables.com/model/1076960-radiator-towel-hook to make it stronger.
It needs to be printed with one support and it has space for magnet 8x3mm (8x2.7 measured with calipers in my case).