If you have a Dollar Tree nearby, you have access to inexpensive tunnels. Look for the
Stack and Nest Bins. Flipped over, they are great hidey tunnels, and the pigs can pull them around with their shoulders like little hermit crabs.
They also white micro-fleece polishing cloths in the auto section that are very soft for bedding. They wash really well, I have some that have been washed weekly for 6 years.
Then look for chenille polishing mits, also in automotive. Sew the open side shut so piggies can’t get stuck inside. Hide pieces of veggies in the chenille so they learn to forage.