Someones junk can benefit others. That means materials can be recycled or reused and are not fully thrown away. This is of course better for the environment and also a lot cheaper. A scrapyard business is not really a secure business. It has a lot of uncertainty. Prices of scrap metal go up and down, there are a lot of legal rules and it can be a dangerous place. Most workers learn by doing.
Bodystorming helps designer to understand to experience real-world constraints and scenarios. They immerse themselves in the actual or simulated environment where the product will be used. An advanced form of bodystorming is Embodied Storming. The participants physically perform the design scenarios. It encourages rapid generation and communication of design ideas. It Provides insights into human behaviors and reactions in real-world scenarios.
Prototypes shouldn't be fully designed. Its important to create a couple of variants that focus on a purpose. Different people have different expectations, so its important to let different users try out the prototype and clarify what the it demonstrates.