To help reduce waste, the world's largest musical instrument string maker D’Addario & Co., and global recycling organization TerraCycle, have a proposition for musicians: send in your used strings and get redeemable points. The program, titled "Playback," deploys Recycle and Restring events at venues like the four-day Bonnaroo Music + Arts Festival that just wrapped in Tennessee. Cleanup crews are cleaning that up as we speak.