(I attempted to scan and post some of these thumbnails but if you remember from class, I did them with a 2H pencil so they were basically invisible.)
With Crystal Castles I am really feeling the idea of fractal imagery, either the use of well placed triangular interactions or the use of fractals to illustrate an abstract castle of some sort.
After class yesterday Reuel sent me a link for some really inspiring fractal images by Artëm Gridin:
This is a nice example of what I meant by triangular interactions... the fractals creating some sort of mass
I would use this sort of technique to construct my castle form