I see. You basically have a guinea pig "C&C" cage (the two 'C's being for Cubes and Coroplast).
Personally, I don't favor coroplast for rabbits because they
do chew it and it is very slippery -- sometimes even with fleece on top as the fleece may slip about.
'NIC' is often the term used for cube cages for rabbits (NIC standing for the brand name of Neat Idea Cubes).
Here is a tutorial for how to make a NIC cage:
http://breyfamily.net/bunnycage.html
It is basically just about identical to what you have except for the coroplast. Instead, they use wood, or wood with lino or vinyl stick tiles, or carpet, or seagrass mats, etc. By seeing the tutorial, it should provide some alternatives to use.
Of course that tutorial, though considered a "standard" by many, is not the only way to make a NIC cage. I'm attaching a photo of one of my old NIC cages just to show you some flooring alternatives. I used a piece of rolled linoleum for the base (no wood at all). I just laid the lino down and was sure the edges were just beyond the cage walls so bunny could not access them. I was able to use scraps of carpet (again, no wood) on the upper levels.
Another
temporary cage I had also shows carpet on the bottom. The upright wall is plain drywall. That is safe for bunnies to chew. Just another example. Please note that this smaller, temporary cage was from years ago. I no longer use water bottles (only bowls) nor do I use those corner litter trays (only use large rectangular boxes now).