So so fun! Use bubbles from dollar store! Dye them with food coloring. I've done this several times. Always a great time. Use water color paper, const paper, even a blank canvas.great art for any wall. (I have one in my bathroom.
I could also see this used on making our cards. Wipe a stamp pad across the bubble wrap and press onto the cardstock. Bubble Wrap Paintings - paint with acrylic or tempera on sheet of bubble wrap. Press clean sheet of paper on top.
Watercolour triangles 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?