Hi. i'm planning on purchasing 2 of the Martin's playpens, the small one with the tray to use like a cage. I'll order extra spring clips so I can attach the tray to the bottom. And the larger 44/44 one. That one will be a playpen for the future rat. I had both before and loved both. The only thing I didn't like is no tray is offered for the large size. I asked Martins and they just emailed back that they cannot make one. My housemate is ok with the playpen, she just asks that there's a tray under it. She's also thinking of using the pen for the guinea pigs when it's free, so an improvement for them as well. Has any one come up with a successful, waterproof chew proof tray idea for that playpen/ Otherwise it's perfect. And if any one knows where i can find them at a better price (say someone is selling used or there's a heck of a deal someplace) let me know. i'm in ny state by the way. Thanks so much.