I have a number of micro-controllers that I like to mess with from time to time. Above is some of my collection. The top row left to right is three Raspberry Pi 3Bs, a ROK64 and a Beaglebone Black. The bottom row is three Raspberry Pi Zero Ws, two Ardunio Unos and a Metro MO Express. I have a few Photon Wifi, Feather MO Expresses and ESP8266 as well. The lovely thing about the new Metro MO Express is that it works great with Ardunio Uno shields yet uses Adafruit’s fork of MicroPython called CircuitPython.