Best material for under a puppy play pen? I'm about to get my very first dog!!  I'm bringing the puppy home next week, and want to set up a play pen. I live in an apartment with hard wood floors, and want to have some kind of flooring in the playpen to protect my floors and also be waterproof as I'm sure there will be accidents as we work through puppy training!  The pen I'm looking to get will be 32”W x 96”L. I'm just not sure what kind of flooring to put underneath it. Any suggestions would be greatly appreciated!