we found these rubber wood boards (9.5 by 6.5 inches and just under half an inch deep) that were oddly being sold as chopping boards, now i think for chopping boards they are a little on the small size, but for giant coasters they are perfect. voted with the force of a billion burning stars. most of the notes for this phase are technical, and will have to be re-adjusted after testing. particles in a solid are packed so tight that they don't move. some time next week i want to put a fish in. 