If it's a big enough clamshell type kennel, it may be possible to put wire through the middle where they come apart? We've done that to fit more rabbits or adult rabbits of different genders into on shipping kennel. Still, it'd be a PITA to clean.
If you have access to your local dump, used refrigerator racks are pretty good for rabbit hutch walls. Not good for floors, though, bunny feet go through the cracks when they run and then there can be a broken leg. For the floors, you want those to be replaceable anyway since that's the part that will rot out first.
I wonder if you'd be able to get the big shipping kennels, split them into a top and bottom half and then put them on a wire floor? Hmm, make a slanted waterproof tabletop of some sort which slants back to a collection trough for the bunny berries and liquids, probably a three in twelve slant would be enough to make it more or less self cleaning. (three inch drop for every horizontal twelve inches, it's how they calculate roof slopes). Then make a wedge shaped walls to put under the clamshell halves to bring them to level. Put 1/2 x 1" wire across the top of those walls for the floor. It will probably need a support across the center. If it were me making it, I'd use wooden 2x2s to build the wedge frames that the clamshells would sit on. Those floor units would be replaced when the floors rotted out.