Thanks for your questions!
Please take a look at my answer to this question on the discussion forum about materials choice and use for your project. In short, this will be up to you to determine which materials are most appropriate and available locally to be used in your project. It will be up to you to research what is available. The FAQ: Big Tricky Documents (linked in our Resources section) can help guide you in how to get started thinking about this.
Let me know if you have any more questions!