I agree with GJ. Luna went from closed door to baby gate – or as I like to call it/mine the “pet containment unit” (PCU) since she is not a baby
– and she’s ok with it now, but when I put it in front of a doorway to a room that is usually closed, she chews and nips at it because she wants to go in that room to explore it. I have the “North State Supergate Classic Safety Gate” and it’s very sturdy – kind of low height-wise though.
I have used timeouts before with mixed results of success. As for your questions on the water bottle and coin jar shaking, I personally am not a fan of its use, but I’m not sure whether or not it is actually “psychologically harmful.” Buns are smart, but they do not mentally understand punishment the way dogs and cats do, so they won’t really react to punishment like dogs and cats do by stopping the “bad behavior.” When Luna nips at the gate or tries to get at some electrical cords, I just gently scoot her away from the area…sometimes multiple times
. Eventually she gets disinterested.