how can I make a removable mural with heavy MDF shapes, using magnets?

Hi there, I'm trying to make a mural for our school, using MDF shapes that will be painted by the children. The mural needs to be removable for when the wall needs repainting. Somebody suggested adhesive magnets. Are they strong enough to hold pieces that are around 1,80m high and weigh over 6 kilos? I was hoping to use 1 or 2 screws on the bigger pieces, just in case they slide. Anyone has some experience on this?

You could definitely use magnets.
For example, a pair of 13mm by 6mm discs of N42 and a bit of superglue would securely hold over 6kg. If you were in the US, 30 of these and shipping would cost you $20.

But you could probably find hook-and-loop fasteners (Velcro) much more easily.

Easier still might be to drill angled notches into the backs of the boards, so that the heads of screws fastened to the wall would slide and lock into place.

A couple other thoughts:
  • I hope you choose the paint carefully. Fiberboard does not respond well to moisture.
  • A 180cm*180cm*1cm square of MDF would weigh at least 20kg.