This one is a blast from the past - they were all the range a few years ago

You simply cover a baking tray and then make little squares with magnets on the back and they are re-useable

Magnetic advent calendars made from baking trays. I had one in my classroom each year and the children loved adding the magnets and got a gift each day too and one in the house.
The one in the house has since bitten the dust but I now add the pictures of the cats everyday to the fridge





Version 2