i use newspaper Zira has never shown an interest in shredding it & his whiffle balls & millet dont get poop on them. sometimes it gets annoying though because poops get caught on the grate & its hard 2 see them :

I buy white, case lot photocopy paper when it is on sale and put a layer of paper towel underneath it so if the wetness seeps through the paper, it doesn't get stuck to the plastic tray. I read a good article on sand paper once but I can't remember what it said other than it wasn't a very good idea. :greenb: