Just be sure that none of those paper bags are waxed, including staples or taped in any way. Prior to making the toy make sure if there's anything like that to completely remove it so it's safe to play with- just like Whiterabbitrage mentioned!
Also, you can grab the kraft paper bags that are in the grocery stores, I stuff them with hay and bits of dried rose, calendula, mint and dandelion for them to shred through. I tied the end of the bag with a chew safe rope- sisal and let them destroy it >.<
Hi Peaches and Cream! If you don't mind toys that are already made, I've purchased a few toys from Bunadventure Series, they have some interesting enrichment toys that can help!