Rubber matting or mat (Blackpool FY1)

I’m looking for an old rubber mat to cut holes in to make a drainer for a litter tray. So the crystal litter will last longer. So rubber stable matting used for horses or a car mat or car boot liner. Doesn’t matter if it’s old or has holes so long as it’s made from rubber not plastic which absorbs and holds onto the smell of urine. Not sure about bath mats, if they’re made from rubber. Or kitchen sink drainers. Thanks.