Download of Wiinstrument 0.2 for Mac was available from the developer's website when we last checked. We cannot confirm if there is a free download of this app available. Wiinstrument for Mac lies within Audio & Video Tools, more precisely Editors & Converters. Please check the Mac app with an antivirus before launch as it is downloaded from the developer's website, and we cannot ensure that it is safe. The actual developer of this free Mac application is Tobias Moebert & Sebastian Burkhart.
From the developer:
Wiinstrument is a multiplatform MIDI instrument controlled by a Wii remote and a nunchuk controller. The controller is available separately and can easily be connected to your computer via its Bluetooth interface. The tool features a graphical interface with OpenGL graphics.
You may want to check out more Mac applications, such as The Wiinstrument, which might be similar to Wiinstrument.