I have at times used plastics (such as polycarbonates and polyethylene terephthalates), melting them, heating them to the point where they curl, using them as colour in rings and brooches.
Other materials I have worked with include steel, wood, cardboard, fabrics and fur.
Most materials dictate what you can do with them. Their hardness, brittleness, flexibility, reaction to chemicals and heat, archival qualities all modify how you work with them. So there must be a considered response to each material in order to meet best practice.
This means that the found material tells you what it can become, rather than the reverse.