I now have a functional model of the stomach, small intestine, large intestine, bowel and rectum! Makes for some fun class and variable names… My current stumbling block is modeling calorific usage and the metabolism. Energy used and how fat, protein, body water and glycogen all balance out and are used, possibly this is going a little too far. I think I need to stop re-factoring idly, and concentrate on this, the last of the physical components I need for my human simulation.