Been working on this off and on. Main goal is to make flexible rivers and area terrain, so have tried some various base materials - dry wall tape, landscape cloth - and then applied acrylic caulk and grit before painting. C&C welcome.
The basic table. Cigar Box mat pinned over felt and insulation board.
Areas templated in.
Area terrain templated more precisely and some signs of progress.
Further progress still...
A local farm.
Beginnings of a marsh.
Where it stands now.
And couldn't resist a test game on it, tho there is still more work to do.