I started with a $3 cabinet door:
I lightly sanded down the door and then I applied Rust-oleum Magnetic Paint. I compared the Rust-oleum to the Krylon magnetic paint and the Rust-oleum got slightly better reviews. I bought it at Lowes and had them stir and then put it in the shaker. Do this if you buy this stuff!
I applied 3 coats of the magnetic paint primer being careful at the creases...
Then I checked to see if it was magnetic. It was so I then taped off the inside so the outside could be painted white.
Then did the reverse so I could paint the inside blue. The blue was a mismash of Sherwin Williams and some other acrylic paint I had on hand.
Ohhh pretty blue-green color being applied to the middle!
After waiting overnight for everything to dry, I used a stencil to apply the word "Message Board"
I'm returning to work in a few weeks so this will be coming with me. I'm going to be making myself magnets and add some knobs or basket to the bottom. It's very likely that I'll make the decision when I get there.