Or perhaps the Gniloi Tikitsch river for our Korsun pocket game. The basic construction is some old acrylic sheets dusted with white primer. Some were used to make the icy banks, while the rest was painted a milky brown for the river. Unfortunately when turned over the white was to dominant so I gave it a coat of oak varnish, which gave a nice flow effect.
The banks are just caulk and stones textured and painted to match the rest of the terrain.
Total length is six foot.