How to build an alternative C&C type cage
You can use linoleum, peel 'n stick tiles. Just make sure it's easy to clean and unlikely to collect/hide dust, mashed poo, dried urine, etc.
It would be a good idea to use grids or some other wire enclosure in addition to the side walls since some pigs like to jump. The coroplast sides on my cage are about 6-7" tall, but when they stand against it (during salad time), they look like they could jump or fall out. I wouldn't risk it, which is why they're surrounded by grids.