In Wolverhampton, we are fortunate to have a super art supplier called ‘scarf4art’ http://www.scarf4art.co.uk/ In brief, scarf sources its materials from local businesses waste! The stuff you can find is gold, and a bagful of interesting bits and bobs can cost as little as £5!! You have to go to see what I mean, but if you want interesting, stimulating, random resources, scarf is the place for you!
Should you not live in Wolverhampton then use this website (https://www.scrapstoresuk.org/) to find a scrap store near you, and trust me, make time to visit it! Your treasure boxes/ tuff spots will never be the same again!