The sketch was a great starting point, but I suspected it would be unworkable as a 3D concept. This hunch proved true as I took my first pass at constructing it for the final game. I made the outer shell of the model resemble the outer shell of the sketch as close as possible. But that was indeed unworkable. So taking great liberty with the sketch, I fashioned a proper nautilus shell by lofting a spiral. I then created the tentacles out of other lofted splines, taking careful considerations of the polygon count limits needed to make the model usable in-game.