I use materials I find on beaches. I have been doing this over 10 years now. I am lucky enough to live in a place with lots of nice beaches, Pembroke-shire (Wales, United Kingdom).
I try to use what I find and so have learn to use a very wide range of materials, including beach glass, metals, plastics and some organic materials like bone or shell. Broadly speaking I make pictures from beach glass, plastics or metals on slate, and useful or decorative articles from these and other materials.