Bare conductive has made a board for playing MP3-files on an external speaker. The sounds are stored on a micro SD card and you trigger the sounds by touching metal points corresponding to the files. However, the metal points can be extended by crocodile clips, cable, foil or anything metallic. This opens up for using your imagination to create a shape or space that plays music or sound effects when interacted with.
More details here: https://www.bareconductive.com/shop/touch-board/