And when I say quick, I really do mean it. 5 minutes tops! ;-)
Self-adhesive chalkboard foil. Sometimes it’s called chalkboard vinyl or chalkboard contact paper. You can find it on eBay if you can’t find it anywhere else.
Pair of scissors
And some chalk!
Cut a piece of the foil to fit the size of the glass, remove the backing paper, stick to the glass and put the glass back in the frame. And that is it! You could also do this with a larger frame of course.
And because the foil can be removed from most surfaces you can also simply stick the foil anywhere you like (although maybe not on your painted walls because it could peel off the paint..!) – imagine the possibilities, chalkboards anywhere in any shape you like!