I want to add some shelves to an internal wall in my unit for my cat to bounce around. She's about 5kg. Problem is that wall is pretty cheaply made, with thin metal studs and plasterboard. No insulation. Even the air pressure of opening the door makes the wall move slightly, if I had a slightly fat cat jumping around on it, it would sound like an avalanche, and no chance any shelves would handle that kind of dynamic load as the studs are so thin.
Obviously I'm going to have to get in the wall by cutting out bits of the plasterboard. What would be the most effective change? Was thinking wood inside the metal studs that can be used for better screws, and some form of insulation to dampen vibrations. Any other suggestions other than completely rebuild the wall?