I've been making detailed pictorial mosaics from bottle caps since 2000… putting me among the first few contemporary craft artists to put a fine art spin on a folk art tradition.
Bottle caps have long been used as a decorative element in folk art. Usually, they are deployed more as a texture, without sorting for color. My own bottle cap mosaics were initially inspired by Haitian ritual flags, in which detailed images are realized entirely through the use of sequins. The first bottle cap pieces I did were large mosaics combining bottle caps with vitreous glass tile.
What I like most about making fish mosaics from crown caps is the way the overlapping texture of the caps does such a good job of representing scales. These fish have been one of my big sellers… I don't make a lot of them, because they're far too labor intensive to actually be profitable but I love the look of them so I doubt I'll ever completely give them up as a medium.