To control the LEDs, [Mukesh] is using an Arduino Nano and an HC-06 Bluetooth module that’s linked to an application running on an Android smartphone.

The Gesture Keyboard is a device that translates gestures into letters. It’s made by an Arduino Pro Micro, an HC-06 module for Bluetooth communication, and an MPU-6050 accelerometer.

The HC-05, a Bluetooth to serial bridge, can be found for around $5 on the internet and therefore may be the cheapest way to add Bluetooth connectivity to your project. However, its default setting… ...