It certainly wasn't done in the normal way but it seems to work and be rather effective. As space is at a premium in the 'cupboard' I decided to use the Mars boards I've made and double them for our Robin Hood project.
The boards are 50mm deep as the Martian canal is this depth so there's plenty of space to play with on the underneath of the boards and as most of the Mars boards are plain it seemed a waste to leave them untouched.
I stared off with a rough layout of the castle parts that had already been done to allow for the positioning of the moat.
Firstly, two cut outs on two sides of the board were cut out to represent the cross section of the moat. Then, the interior of the underneath of the Mars board was built up first with a 30mm layer following the course of the moat and given a rocky texture by basically ripping out small chunks of the foam. On top of this a sheet of6mm acrylic was cut to fit inside the board but with two tabs where the moat crosses the edge of the board.
Then the final top layer of thin foam was cut and shaped to size for both sides of the moat. Before any of this was stuck down the acrylic was painted underneath with a browny green wash and the same wash was applied to the moat bed and sides. After this was dry it was stuck to the bottom foam layer with copious amounts of thick superglue and left to dry for a couple of days. Once dry the top layer was applied in the same way and left to go off.
An extension from the none castle side was made under the water out of styrene sheeting to allow the drawbridge to lower, as the drawbridge can only be a certain size this extension of the ground was needed (it will make sense in a photo later on).
Once the top was thoroughly stuck it was given a coat of sand but not where the castle sits as it makes it much easier for transporting. When dry, the sand was washed with dark brown ink and drybrushed up to try and match my existing boards.
Here you can see the extension from the ground towards the gate and before the top layer was applied and sand etc added.
Greenery was added here and there and inside the castle walls was painted brown with limited grass in the corners. THe drawbridge was made from balsa and I am in the process of making a couple of small loops that the bridge lowering chains will come through. The drawbridge will remain removeable for ease of transporting.
Below are a few shots of it complete and hopefully very soon I'll be making another board that will extend the castle down one side.