One of the things I love about skirmish gaming, especially the Rattrap games (Hi Rich!

) is that you don't need masses of scenery to cover a monster-sized table. Starting a new scenery project doesn't have to mean "Oh Dog, I need 8 feet of riverbank..." - it means you need two or three feet!
Hence another 'quick' project - two 12" sections of shoreline or riverbank, made from mattboard. MDF would be more durable, but takes time and tools I don't have, and mattboard is tough enough.
Each piece is 12" long, 4" deep, with shoreline on one edge and the other edges just straight to match with each other or the table edge.

Basic paint is done on the water - pale blue, dark blue & black, blended with a damp 1.5" brush.

I need to do touchup on the water yet - I'll butt the two pieces together both ways so the ends blend a bit, and touch up the lower one somewhat - the upper one has more of the look I want.
After that it's several coats of gloss acrylic varnish - probably at least three or four - then paint, flock and details on the shore sections. There'll be a couple of sandy beach sections, but most of the shore will be mud/grass & foliage.
I might eventually do more sections - two more this size would let me run a wide slow river right across a Rattrap-sized table - but for now two is enough.