Amazon Cage Liner
https://www.etsy.com/listing/754151580/15-381mm-big-wood-running-wheel-exercise?ga_order=most_relevant&ga_search_type=all&ga_view_type=gallery&ga_search_query=chinchilla+wheel&ref=sr_gallery-1-22&organic_search_click=1&cns=1
would these work?