This is an idea I had a long time ago, and I've moved on to experimenting and making things. The first little thing I did was simply plaster a polystyrene box with hypertufa and paint the inside with black pond paint- pretty uninteresting I know, but what if I made a much bigger one with built in plumbing I thought. So I got a couple of big bits of insulation poly, cut them up and glued them together like this- I melted channels into the foam for a bottom drain and some pipes and valves. Its to be hooked up to mains water, and its going to be used to irrigate a little vege patch. I wrapped it in welded wire, which I separated from the foam with coreflute strips. Then I plastered It with cement render I wrapped it in plastic to keep it moist while the cement cured. Then I painted it with liquid rubber pond paint and it was finished I wasn't happy with it for a number of reasons; 1. I shouldn't have cheaped out and used thin poly pipe. I should have spent a whole lot more and used bigger-bore pvc pipe. 2. I shouldn't have used to thinner layers of poly glued together in a herring bond pattern. I should have just used one thicker piece, and glued it together like a big aquarium. 3. Wrapping it in welded wire took more work than the rest of the build put together. 4. The coreflute strips made the wire too far away from the poly, resulting in the render being about 12mm thick. While its extremely strong, the pond weighs nearly 90kg. Its heavier than it needs to be.