[sushi_78]

I think the bottoms of both cages may sag due to the weight of all the bedding and other cage contents. I had this issue with my Living World Eco Habitat which is a 100cm cage on wheels. I fixed it by adding additional wheels apart from the four at the corners to provide more support. I think the base should also probably be thicker than 12mm.

For the top cage, you might actually need some kind of metal bracing.

This cage makes me a bit nervous to be honest. It looks lovely, but I'm not sure how structurally sound it is especially when made of Ikea panels which are often compacted cardboard with a plastic veneer.

The height also worries me. That top cage is going to be incredibly heavy and the whole thing could quite easily topple over, potentially onto a pet or person. It needs to be fixed to the wall to be safe (which defeats the purpose of the wheels).

Have you considered making the cages separately and placing them on a heavy duty garage shelving unit? It will be better designed for such heavy objects.