Over the years, I've pried tiles from discarded display boards and collected tile scraps from contractors for use in mosaic.  Here you can see that I scraped the adhesive and mesh off the backs of each tile and carefully placed them into a design.  This is something like mosaic, but I didn't cut the tiles.  It is more like custom tile.

I set the tile onto the sticky side of contact paper, and when I had finished arranging and rearranging the tiles, I held it together with tile tape.

Below is the backsplash taped together, waiting to be set into mortar.  This double indirect method makes it easy for me to help a client to customize any tile wall, shower or backsplash because I can make a mosaic of any size, tape it together, and it can be inserted into any tile grid.

And here is another shot of the completed backsplash.  The room is decorated with vintage appliances and soft sage and yellow tones with copper accents.  The tiles have a retro look, but it's simple, classy, and easy to clean, and much more fun to look at than your standard tile grid.