A few years back I helped Mrs. M make a magnetic chalkboard. We found the perfect frame at an antique shop near my house at the time, we cut down sheet metal to fit the frame, made our own chalkboard paint and voilà! Her Magnetic chalk board was complete. I intended to immediately make one for myself & CPB, and I did (eventually) this past Christmas.
You can see the instructions for how to make the chalkboard with the link below, I learned from a few problems Mrs. M & I conquered with her project.
1. Search for sheet metal and then find a frame to match the sheet size.
Cutting metal, even thin metal, was a pain. Our hands were sore for days. Aaron Brothers or Michael's have a good assortment of frames, the antique frame we found for Mrs. M was lovely but an irregular size.
2.Your paint color will change when you add grout and after you season the chalkboard.
Find a paint color that coordinates but expect it to change slightly. For Mrs M, we selected an espresso brown, we added white grout, expecting it to lighten some but after the board was complete and seasoned the paint looked darker.
3. Pre-made or homemade chalkboard paint, chose the best option for you.
Pre-made chalkboard paints are easy and fairly inexpensive if you plan to paint a small area. Making your own chalkboard paint lets you customize the color and allows you to make as much or as little as you need.