Principle 34. Discarding and recovering

1. Make portions of an object that have fulfilled their functions go away (discard by dissolving, evaporating, etc.) or modify these directly during operation.
   Use a dissolving capsule for medicine.
   Sprinkle water on cornstarch-based packaging and watch it reduce its volume by more than 1000X!
   Ice structures: use water ice or carbon dioxide (dry ice) to make a template for a rammed earth structure, such as a temporary dam. Fill with earth, then, let the ice melt or sublime to leave the final structure.
2. Conversely, restore consumable parts of an object directly in operation.
   Self-sharpening lawn mower blades
   Automobile engines that give themselves a "tune up" while running (the ones that say "100,000 miles between tune ups")