After gluing the craters, tiles, styrene sheet and tyranid bits in to place, I started work on creating the texture of the gaming board. The goal here is for something slightly Martian, or barren world / asteroid. Whilst the final colour may not be red, the idea is to have a gaming board that is representative of a cratered world. To achieve a good texture basis, I used a lumpy composition of polyfilla mixed with grit and water. Some of the polyfilla in the image is slightly a different colour: this is due to a different compound being used and a little bit of brown paint added in for good measure. Although I'm aware that if my painted polyfilla chips it'll reveal the underlying colour, I figured that it'd take too much paint and trial and error to achieve a colour match with the eventual overcoat.
After the texturing using the polyfilla, I used three different grains of sand (with PVA glue): a very coarse grain that I used next to the primary ridges and adjoint to the craters, a finer (red) sand for the main part, and a very fine (black) sand grain to complete the effect. Noticeable in the image is that I've tried to stick the sand grains on one side of the craters to make them feel like a wind-swept planetary surface.
I will probably use a bit more polyfilla on the lower board to create about the same percentage of texture coverage as the upper board in the image before progressing to a painting stage. But overall, I'm happy with this level of detail so far.