You obviously need depth to convey the swamp area. The best way I found to do this is to stack the ¼" plywood in different layers. The board you saw in the previous section is the board I cut up with my jig saw and then layed the pieces out on another 2' x 4' plywood sheet. Where I had three layers of depth, I just layed left-over pieces of playwood down to support the upper layer.

Before you start texturing, you will want to round the edges around the ponds and any transition between layers of plywood. I suggest using a drill and a grinding bit to shave these down. Now that you have smooth surfaces you are ready to texture the ground.

Instant Paper Mache (IPM) is one of my favorite substances for texture. I don't suggest using it on foam core since it is water based and will warp it but on wood it does just fine as long as you don't saturate it. Take the IPM and just press it on the wood where you want it to look like mud till it is smooth but still bumpy. Fill in all the areas around the pond between the layers of plywood but not in the pond (unless you want some shallow areas).