My apartment only has one door, but I have an aluminum bi-fold door that "hides" my air conditioner and water heater units. I hang my Angel Bambi's leash on that and if I was on the computer or not paying attention, she would walk over and tap the leash, making the metal clip "dink" on the aluminum and then stand and stare at me. This was a self taught method for attention, as someone else said earlier, our Shelties are so smart.