Mouna Andraos and Melissa Mongiat of Canadian design collective Daily Tous Les Jours designed the 21 Balançoires (21 Swings) project in Montreal, Canada. Using pre-recorded sounds from a xylophone, piano, and other instruments, they programmed color-coded swings that play various notes. When you swing in unison with a partner, more complex melodies and harmonies play. If only every playground had such creative construciton.

[via Colossal]