Spray

rattle the can. hold still and it drips.

spray-paint a wall from a rattle can; linger and the paint runs

paint lands over time under the nozzle, not over the distance it travels: move and it spreads thin, stay and it piles up and runs. rattling mixes the can back to a fine spray.

Concepts: fluid-flow, gravity, color, touch, time.

An interactive you play with one thumb, on Wundr.