Inspired by the simple robot Bob, this is an ESP8266-based version.
It uses four HK15318B ultra-micro servos, mostly because of their tiny size and the fact that they work well powered by 3.3V.
It runs the nodemcu LUA firmware on the ESP-03 module. The servos are connected to pins 12, 13 and 14, with the two foot servos sharing a pin – that's because I can only have 3 PWM outputs, they they always move together anyways.
Not much more, really, a 1S LiPo battery, a power switch and a pair of LEDs so that I can see when it's on and when it's off. I want to add an IR distance sensor to it, but I'm still waiting for it to arrive.