Another evening dawned, it was raining outside and I was working in the shed getting ready to toss a bucket-load of insta-filler and pva glue (both mercifully cheap at the local Action) at my work in progress. I want to spray paint my polystyrene and that means it needs to be well sealed off. You can do this by covering it in PVA glue cut with water (a 50/50 mix will do). But as I also wanted to make my cliffs look like cliffs instead of haphazardly glued polystyrene I need some insta-filler too It gives a nice texture and if you mix it with PVA it becomes rather strong and easy to paint. I made a mix consisting of about equal parts of water (for ease of applying), PVA and insta-filler and threw in a bit of beach sand because I was feeling creative and adventurous. I covered deep gaps and seriously sloppy work with a bit of pure insta-filler and covered it with my mix later.