Practical Ecology portrays a 74-year-old man, born during the World War II, demonstrating objects he's invented. He has for example made a wooden cutting board out of an old leather sofa and skates out of old skis. All of the objects are made of found objects or waste which has no other use. The importance of the objects for him is in the invention, in completing the thinking process by using his skill of making something out of nothing, regardless of how useful the final object may turn out to be. The value of the object is defined by the invention and time spent to create it.