Bass ferret pans are the ones specifically made to fit ferret nation and critter nation cages.
We provide a ton of wood. We get lots of fresh apple locally then right now we have a box with kiwi, pear, pecan, hickory, and cactus twigs and chunks from various online retailers. Each cage gets a handful every day and a new 2-4' apple branch every cleaning. Woven willow items are usually a huge hit but messy and destroyed so fast it isn't really cost effective to keep some in the cage all the time. It's more of a monthly treat for ours.
Plastic free bird toys are generally safe and provide a wide variety of chewing materials. Often they ignore them and ignore them until one day they just destroy the thing. Our cage of young females decided to kill their bamboo and coconut bird toy this week. One day it was whole and the next they had stuffed all the hard pieces in the pvc tunnels and hauled the coconut husks flattened in to chewable discs down to the bottom level. Today they drug it all back out again to carry around the cage. I usually take the leftover pieces from destroyed bird toys and put them back up on those metal kabobs. You can buy your own toy making supplies including natural hemp, jute, or sisal rope from parrot sites like
http://bobosplayhouse.com/ and some chinchilla sites. I also find some really random stuff on bobo's playhouse like a 25' grapevine for $10. That actually had to be thrown out from dirtiness before it was fully destroyed. Sometimes you can find safe supplies at craft stores and that's where I got my hemp rope but sometimes the stuff is treated so it's best not to do that unless you know what you are looking for.
There are all sorts of fleece items to buy. Hammocks, houses, tents, tunnels... Some people cut pvc in half, cover it in fleece, and then bolt it to the side of the cage as a curved sleeping ledge. You can find finished pieces from online sites. Fleece for furries gets mentioned a lot on other forums.