Use painters tape to stop the paint from getting on the edges.
Color all the surface area so that when you write on it for the first time, it won't erase well.
You can use regular hooks, or magnetic hooks so you can always remove them and use the pan as a tray.
Again, this is optional and depends on your design.
Apply a layer of Mod Podge on the tray, place the craft paper and then apply another layer of Mod Podge.
Apply some magnetic tape to anything you want to place on the magnetic board.