Don't you hate it when you struggle with a project labeled "Easy" . I saw this tutorial here. I had a lot of cardboard and thought it would work as well as foam board. I was wrong. They looked very "homemade"-but not in a good way. So I drove to the craft store andI bought some foam board and re-did them. They looked great, but then I noticed that 2 of them were the wrong direction, so I re-did them. All of this made me too frustrated to take "during" pics, but the original one has lots of pics.
The original didn't have measurements. Mine were 10 inches high and the end pieces were 2 inches deep. I removed the molding at the top of my blinds and then duct taped the pelmet box to it and re-hung it.