industrial design – Resources on the design of "outdoor physical shell" of a home appliance product?

I am interested in learning how to design the shell / enclosure, such as the plastic case of a humidifier.

Some things I can think of are:

  • Perspective. How it is fashioned and refined. And finally perceived by the customer, by the look and the touch …
  • Equipment. The shell and the coating. On technical requirements such as strength, weight, thermal stability, toxicity …
  • Cost. cost of material and difficulty of manufacture.

I especially want to learn more about the prospects and the costs. Ideally, I only want to know some materials commonly used in industrial production, their applications and their respective costs.

I tried to search the internet without success. I hope someone can help.
Thank you