from what i have seen in stores, that is the 'gnawsome hut' or some such name, and it is made of plywood.
fleece liners for the cage bottom don't necessarily need to be sewn. quite often i will just fold a large piece of fleece in half so that it is two layers and the same square footage as the cage bottom (just shy of 2x3 feet by the way, is this cage's floor space). works great, and if my boys don't pee on the fleece too much, i get an extra day or two out of it by shaking it out, opening up the fold and folding it 'inside out'.
Well I got in a fight with the sewing machine during the hammock making, but we reconciled, put our issues behind us, and moved on! Soo to expedite the process with the floor liners I just made them way too big and sewed the outside shut, seems exposed, but they should be well away from any chins reach outside the cage! BTW I added 2 extra pieces of double thick felt in between the layers! These 3 pads are like pillows and should help soften any falls!
Hammock and chin safety proofed ferret sleep cube! Took the fabric straps off and added fleece ones, and took the fabric off the opening! Not sure how long the opening will last but we will see!
Dust baths are helping! She's still dirty though!