The project stemmed from a need to retain these controls whilst hosting a tenkeyless keyboard in my current setup.
The macropad uses a minaturised Leonardo board from Jaycar electronics. However any board with USB HID functionality such as a Pro Micro would be also suitable for this project. Making up the core of this project is the consumer API from NicoHood's HID-Project. Through the use of the multimedia functions within this API, the macropad is OS agnostic and is plug and play for your multimedia control needs.
Maso
Mirko
Artem Kashkanov
Jeremy Hong
Micro looks like a more expensive dfrobot beetle https://www.dfrobot.com/product-1075.html
I used one to make a similar small 3-input macro controller with a couple LED indicators