40k Water way pt1

My Latest project I'm wanting to build a canal/Waterway to add to my board which i'm trying to make in a city fight theme.

I was thinking of making it with Masonite(mdf) as the base and polystyrene as the levels (polystyrene since in SA the pink foam is hard to come buy and is expensive. And I've had good results with sealing the polystyrene with PVA and sand.

made by Kendoka on Warseer

I was wanting to do this with out making a whole new board and so no depth.

So far I did some planning with in regards to what I wanted the final project to look like.
Some of the main concerns was size and having it have to much of an impact on the game (warhammer 40k)