|My original boards with scenery|
I start with a 2'x8' sheet of 1 1/2" insulation foam that I cut down to two 2'x4' boards so I could fit it in my car and store it easily when not in use. I like the 1 1/2" foam because its sturdy while still being thin enough to store in a closet or under a bed (or in my garage now that I'm a homeowner). The 2" version of the foam is nice as well, but just feels a little bulkier to handle and is more expensive. Once home, I laid the the boards out with one of my existing boards and using a Sharpie marker I roughed out the placement of roads and a river section.
Next, I spread latex caulk down on the areas that I wanted to be roads. I use a spatula to spread it and then mark in grooves to represent the roads. When the caulk dries it is strong yet flexible and gives a good impression once painted up.
While the caulk dries, I set about carving out the riverbed. A simple flat head screwdriver is best for this - you simply need to do a good Norman Bates impression and gouge out the river in sections. This is quite messy so its best done outdoors or when significant others are away.
The next bit involves a slightly specialized tool - a heatgun. Easily available on Amazon for $20ish, the heatgun is invaluable for making terrain. It can also be used to shape plasticard into banners, rounded shapes - the possibilities are endless. Just use caution when handling the heatgun, as the tip gets very, very hot.
Using the heatgun on a low setting, melt the foam a bit in the riverbed. This creates a smooth bank and natural feel to the river. As the foam melts, it will give off some really nasty smelling vapors so make sure you do it outside or in a well ventilated area. Wearing a mask wouldn't hurt either. The air filtering kind, not the Chewbacca one you've got in the back of the closet.
Next, I scooped up a few stones from the garden and used some Liquid Nails to adhere them. I let everything dry for a few hours and then started the painting process.
With the caulk and Liquid Nails dry, I coated everything in black latex house paint. I find the black to be an excellent base to work from. Additionally, if the board suffers wear and tear over time it's a little less obvious when the black undercoat shows.
Once the board dries, I apply a layer of playground sand to every inch of the boards using wood glue. After the sand and glue dries, I apply another layer of black paint over the river and its banks and then the rest of the board gets a liberal amount of a mid-brown latex paint. At this point, I left the whole thing to dry overnight.
The following morning I started the process of drybrushing the whole board. This is done just like I do on the bases of models. I used a cheap set of artists acrylics - one in a yellow ochre color and the other in a bone white. The brown areas were drybrushed up from brown to yellow to white and the river was drybrushed with a light grey.
Then I moved onto flocking the board using several shades of Woodland Scenics flock and wood glue. This was the most time consuming step and its best done in sections. After the flock was added it superglued on some random bits of clump foliage and small flowering bushes.
The final touch was to pour some clear resin into the river section. I hot-glued scrap plasticard on either end of the river to create a set of dams that would keep the resin in while it cured. Its key to get a good seal here. One final piece of advice is that if you're going to use resin for the river choose a brand that cures with a low heat. The curing of the resin is a chemical reaction and some can generate enough heat to actually melt the foam - just like the heatgun does. I recommend Enivrotex Lite as a brand to use. Once you've poured the resin, give a few passes with the heatgun on a low setting - this will eliminate bubbles and your river will look better for it. Give the resin a good 24 hours to cure somewhere where it won't be disturbed. Don't leave it out overnight or morning condensation is liable to ruin the project.
Now I have a full 4'x12' set of gaming boards - either to use in one huge table or to subdivide into several.