Mike - I used to use regular newsprint but I switched to unprinted paper. I know the ink is nontoxic, but it gets on everything in the enclosure, most notably my water bowls, and is very hard to get off. And after cleaning, my hands would have black marks all over them. It's great that it works for you, but substrate is really a personal preference thing, that is everyone has their own preference for different reasons.

I went to Home Depot and asked about Kraft or packing paper, and the employee told me they didn't have any. Well that was not true. Just ask where their packing supplies are. It comes in a cardboard box that says "Pack-eze" on it, it's 145 sheets for something like $10. Don't quote me on the price though.