Where can you obtain rubber in sheets like that?

Home depot and lowes has shower under layment which is rubber. 4'x however wide you want it very good price

Get all my rubber and sealants through a contractor I know who does rubber roofing. Been using that same sheet for a few years now. I would imagine any lumber/big box stores would carry it. I use rubber for the convenience that it's easy to wash off. Another great material to use is tyvek or house wrap if you will. You could get an abundance of it on construction sites, they're all about saving space in their dumpsters,just ask first. Any type of material will suffice.

Don't take my comment personal, if anyone is out looking for (specialized skunk proof traps) which believe me there is no such thing. By all means buy them. I handle quite a few skunk on my adc line and the kids set for them during the season, an extra step doesn't bother me. Believe it or not I'm not wasting time by using rubber either. Just my preference, rather put that type of money into something that would really benefit me verses something I could make and have the same results or better.