Since Harry's been working with concrete, and I just went to the demo at Minto House, but haven't really tried it myself yet, he helped me cast a base for the perspective engraving piece today. It's snowcrete, so it will be white, made of 3 parts white stone, 2 parts play pit sand and one part snowcrete. The mould was made of 1mm vacuum forming plastic, and the glue that you use to hold it together is magical. We re-enforced the mould with plaster, just in case.
