1) is clear
2) can be poured to a depth of 4-6mm
3) is available is largeish quantities (enough to cover about 50% of a 4ft X 4ft board)
4) is not too expensive
5) will dry within a day or so (faster is better)
6) is available in Japan (either buyable locally or shippable from overseas)
also, if anybody has any ingenious ideas for modelling huge numbers of bald cypress, let me know...