Guzheng

Twenty-one strings tuned pentatonically, so a sweep already sounds like music

A guzheng is a table-sized zither, about a metre and a half long, with twenty-one strings tuned to a pentatonic scale, so even a casual sweep sounds like music. Picks go on the right-hand fingers; the left hand presses the strings beyond the bridges to bend notes, and that bending is where the expression lives. It needs a permanent spot, and you tune it yourself.