I've seen a few of these floating around and wanted to make my own.

Top most layer ironing on

.2mm layer

no supports for the holes on the back

Magnet holes are for 4x2mm magnets (Which struggle to hold the print up)

I'd suggest double sided tape or making the holes bigger for a 5x2mm magnet.

***Update***

For those that already have 4x2 magnets (Like myself) just glue an additional magnet to each one and it hold up flawlessly!