exia
Junior Guinea Pig
I think it just was the sound of elephantmarch that made me nervous. Bob is our big little bulldozerMine were in a stacked 2x5 when inside. It was pretty secure (lots of cable ties and some wood to support the upper level). The boys lived upstairs. I did worry when they (on a rare occasion) ran around but it was fine, no shifting. Looks good and I bet they loved it!
I would add hides (can’t see if there are two) and more hay as well.

Each floors has at least three hideys, one hayrack and a cardboardbox with "playhay". If they dont get a cardboardbox they get another hayrack, so there's two and no needs for arguing about food.