Hey Grimm,
Once the board was built up with carved (and sanded) styro I painted the whole thing in a bluie/white mix (one part light blue paint, one part white paint, one part white glue and one part future floor wax) let dry. Then I added a bit more white paint to my mix, along with about a cup of woodland scenics 'snow' (I bought a giant shaker full and used about half on this project). Then just keep adding snow and white paint...I think I did 4 more coats. Toward the end I was only applying the snow to the 'top' of the board, so as to keep some detail between the broken ice chunks. Then just to make sure the whole thing was solidly affixed I coated the whole board in future floor wax. Let dry. Dab on a final layer of bluie/white mix (or whatever is left in the bucket...) and sprinkle with a final layer of loose 'snow'. Let sit overnight, shake off exess 'snow', paint the 'water' in a darker blue, seal with dull coat, let sit. Play a game...mmm!...
De-lish-ious!