So, I'm currently working on some scenery for my VaS games. This is how it turned out:
Clicky for a quick how-to:
The following video inspired me to try their technique, so credits where its due:
Made an outline of the island that I want in thick plasticcard
Then started cutting syrofoam in chunks that would fit on the plasticcard outline
After glueing everything together and letting it dry I went completely overboard with my exacto knife on the syrofoam :) Note that except for a rough horizontal pattern I did not 'try' to get rock shapes or anything, just let it all go and cut it up till your satisfied with the result.
Then covered it with a mixture of wood-glue, sand and black acrilic paint to make sure it becomes a bit sturdy and gets a bit of a grainy texture.
After the first coat has dried I made a second run with a spray can of black primer to make sure the black got in every corner and recess.
Finally, after the black undercoats have dried I gave it a drybrush with subsequential coats of dark brown, brown, sand and finally a bit of white.
Finish up with flocking the piece and voila; a nice island for my sea maps :D