Creating a fake brick

About a week ago I had an idea; 'What if I was to create fake polystyrene bricks instead of using real ones, for weight purposes...'. I decided to experiment, I acquired some polystyrene, shaped it into a block/brick shape (although it is bigger than the average brick). I then covered it in Polyfilla to create textures and definition & to make it look more authentic. Once dry, I applied water to some clay, then using a brush I painted the wet clay directly onto the Polyfilla brick as opposed to using acrylic paints. I think the experiment was time consuming and it would be easier to aquire bricks elsewere. This would also give a better finish/result. Anyway, I've included a few photos of the Polyfilla brick ...