I'm very close to purchasing some slate caves/clay cones of E-Bay but I was wondering if anyone has used plastic before as cave material and if so was it successful for breeding? The reason I ask is that you can get plastic water pipe at DIY stores for approx £1.75 for 3M and plastic drainpipe (square section) pretty cheap to, so thats a lot of caves and all you would have to do would be to block the ends of if you wanted to after you have cut it to length. Thanks.