Knob Alert

I'm taking up silk screening and have converted the utility room to a dark room. So I made this thing to "alert" someone (my wife) to the fact that the room they're about to enter is light sensitive. I'll snap this onto the door handle whenever lights shouldn't be turned on in the room. That way, when someone blindly grabs for the handle, they'll feel this thing instead and remember that they shouldn't open that door!