Andrew and I made this chalkboard and it was so easy. The hardest part was finding a window, which out of blind luck Andrew and I stumbled upon.
Step 1: find a window
Step 2: tape edges
Step 3: buy chalkboard paint (this is a type of paint that you can buy at any hardware store.)
Step 4: coat window with 3-4 layers of paint (you must wait 4 hours between coats.)
Step 5: allow paint to dry 5 days before you begin to write on it.
*if anyone would like to try this project let me know. I have an extra set of supplies.