I came across this intriguing gadget on Kickstarter. They have already surpassed their goal by 10 times. The instrument is currently available only through their Kickstarter campaign, which expires 13 April. They have announced no plans to distribute the product through some other retail scheme, but it seems likely that their success here will change that.
The Antiphon is not technically a musical instrument at all, but rather just a MIDI controller device. You need a synthesizer or other software instrument (like Garage Band) to make it sound. What makes it different is the ability of the user to play it in a number of different ways that are software-configured using an iOS phone or tablet. They are working on an Android version, but make no promises about that. It can be used without the configuring software like any MIDI controller, but the software lets you create unique custom configurations.
The video shows the controller being used as a guitar, a violin, a keyboard, and a drum pad. These things always look easier in promotional videos than they turn out to actually be, but it does seem to be an intelligent and ergonomic design. One could easily imagine an expanded version similar to the Chapman Stick, but their design philosophy is wisely to keep it simple. It’s obviously working since their Kickstarter has already sold nearly 1800 of them. We’ll be watching to see how they are reviewed by actual buyers.