And how did I get the picture on the radiator? I didn't want to glue it in case we wanted to use the radiator at one point.
I found the perfect solution for the radiator cover at supermagnete.de.
The strong self-adhesive neodymium magnets Q-40-12-01-STIC
keep things flexible.
The customer service was great because I wasn't sure at first if it would work the way I envisioned it.
If you want to hang something on the wall (or radiator) you need to divide the max.
adhesive force of the magnets by 6.
The FOREX board was not exactly light with its 3,3 kilos, but it worked fine with 20 magnets spaced out over the whole board.