You can build a wireless remote control RGB LED NeoPixel color mixer using two Circuit Playground Bluefruit boards and some slide potentiometers. Using Bluetooth LE, the boards can communicate wirelessly with no need for a computer or mobile phone or tablet!
Thanks to the Adafruit Bluefruit Connect and BLE libraries in CircuitPython, setup and coding are incredibly simple. You can get started quickly and then extend this code to all sorts of other remote projects!
To control the color settings, you'll need three slide potentiometers. These short ones work on a breadboard quite well, any longer and you'll need to come up with more involved solutions for mounting.
Or, if you already have jumper wire: