This week Specdrums launched a Kickstarter campaign to fund their quasi-augmented-reality music rings. They look like fun, and work with a dedicated mobile (iOS & Android) app. They seem to have found an audience because they instantly shot past their $15,000 funding goal. At the time of this writing they are about $50,000 beyond that!
Since the project has been successfully funded they hope to begin shipping the rings in January 2018. If you'd like to pick up a pair you'll need to back them for $74. Their demo makes that price pretty tempting!