I found this amazing window on craigslist for $30 about a month before we left Columbus. I really wanted a chalkboard in my kitchen to keep track of menus and activities. Plus I thought it would be cute.
I spent weeks sanding (by hand because I'm too cheep to get a heavy duty tool) and finally got the 15 layers of paint off the window frame. I didn't sand the wood closest to the glass and gave it a new coat of white paint. I used 3 coats of chalkboard paint on both sides of the glass, so potentially I could use both sides if I wanted. The chalkboard paint is very durable but I could scrape it off if I ever wanted to go back to just glass.
I'm really happy with the way it turned out. We use it all the time for menus, alphabet practice and picture drawing.