The entire fort was repainted in a dark grey with highlighting and drybrushing of the stone work in lighter shades. Then sand was glued to the base using PVA and painted brown after the glue had dried. The paints used for all the colours were latex paints from Home Depot. They often have smaller containers for sale in the 'Oops' section of the paint department. Anytime I pass through there, I have a quick look for shades of brown, green, and grey that might be useful for wargames terrain projects.
I constructed three ravelins from polystyrene foam and mounted them on cutoffs from the original base that were trimmed to give an equilateral triangle. To get a consistent size and shape for the pieces of polystyrene, I first cut a pattern out of cardboard that was used as a guide for my handheld hot wire cutter. The simulated stone work was done in the same manner as the main fort.