let students paint paper with watercolors, wet on wet, similar colors. Let dry and cut into triangles. Students pick triangles and glue down randomly, leaving white around each one. Maybe try with black or other color background?
DIY: Paint Chip Heart Art - Punch out hearts in paint chip samples and stick them on a canvas using adhesive foam circles (to give art dimension). Simple and cute; I'm totally doing this for my bedroom when I get a chance!