Hi all, I'm looking to purchase a 3D printer for prototyping and I have a few questions I hope you can answer for me.

If I buy a 3D printer from the big companies like 3D systems and Stratasys, am I restricted to the materials that they sell or can 3rd party materials be used as well?

Are there any printers right now that are capable doing metal printing and regular plastic materials?

Are there any resources I can use to find specific specs for materials? Mainly ones thermoplastics that can withstand temperatures around 200C?