safe doors for shelter cats

My Sister works in a pet shelter and the cat house is under construction. They have glass doors and fronts, so that the cats can be seen without opening doors all the time. Unfortunately, experience says that cats, especially kitten, may run against the glass while playing or not paying attention. So we decided to  cover the lower 50 cm with that milky foil. And to add a friendly touch, we cut out cats that I "designed" and placed them on top.