original_query: Who are some of the artists known for their works using unconventional materials?
query: Who are some artists known for creating works in POW camps using unconventional materials?
answer: Jack Bridger Chalker, Philip Meninsky, John Mennie, Ashley George Old, and Ronald Searle are some artists known for creating works in POW camps using materials like human hair for brushes, plant juices and blood for paint, and toilet paper as canvas.