The following is a step by step guide to building a waterway and/or river for your DBA battles. Before we get started here is a list of what is required to take on this project:
A sharp hobby knife
0.5mm (0.02") sheet styrene or plasticard
Your favourite sand and grass flock
White glue - use Elmer's, it doesn't contain animals!
Clear, glossy nail polish or high gloss top coat (spray or brush)
Various terrain coloured paints (blues and browns)
Clear silicone or Woodland Scenics Water Effects (optional)
Using the 0.5mm sheet styrene, cut a couple of wiggly strips about 40mm wide. I use a hobby knife, but I have heard rumours that some people use other cutting implements... Either way, the stuff cuts almost as easily as paper, so I am sure scissors would work just as well. When I did it, I made both a waterway and a river at the same time, so from a single piece of styrene I cut one length of waterway and one of river.
Base coat the river black, then put some glue down along the edges, spread it with your brush and sprinkle your favourite mix of modelling sand. Give it time to dry then paint the sand a dark brown (or whatever colour goes best with your board) and then drybrush on a highlight of a lighter brown.
Do the same thing for the waterway, except, if you like, make the ground colour more sand like, as I did above.
Now it's time to paint the water. Start from a very dark blue (deep water), add some lighter blue to highlight, and then finally, add some of the highest ground highlight to the mix for the final highlight. This is important because the ground will both reflect from the top of the water, and show through under it at the riverbanks/beaches.
Now let's smooth out that water surface and give it a little texture. Basically, put some slightly watered-down white glue on the water surface and spread it around. Don't put it on too thickly or it will dry a milky, translucent colour. Let this dry until perfectly clear.
Once the white glue has dried, it is time to gloss up that water. For the small river surface I just used glossy, clear nail polish. This stuff is great for these small projects, but be sure to paint outside or in a well ventilated room, acetone kills brain cells!
For the wateray, I used a glossy top coat spray from the company who shall not be named... I used that one because I won't use it on miniatures ;) It should be put on thickly and let to dry completely. Once again, do this outside and even consider wearing some breath-filter mask or something to avoid the brain damage ;)
Finally, if you want more texture to your water, particularly the waterway, pick up some Woodland Scenics Water Effects or some clear non-toxic silicone. Neither of these require mixing, and both can be shaped. Squirt some down in rows and shape them into waves. You can texture the top of the wave with a tooth brush for more realistic effect. Finally, drybrush the tops of the waves with white and you are done.