That looks wonderful!! Once the flooring is in, it will be a great place for Chocolate Chip.
The one thing about tiles attached to the cardboard— urine might seep through the cracks of the tiles and cause odor and mold within the cardboard. (unless I am picturing it incorrectly).
I was able to get vinyl remnant from a carpet/flooring store for cheap. One piece, easy to clean.
It’s hard to tell what the NIC cubes are secured with, but I know that the little round connectors aren’t enough, so you will need to secure with zipties IF you haven’t already. If it feels “wobbly” or unsteady, you can secure it with dowels cut to size.
I know you were worried about the size of the girds and your young bunny’s head squeezing through those (in an ealrier post)), but it looks like you were able to get the ones with smaller grid proprotions?? If so, I’m so happy for you as in some places they were more difficult to find.
Congrats on a great start! Keep us updated.