Before TongDou had sensors, audio, or a personality, he started as two laser-cut brass side plates and eight 1 mm brass rods.

This short video shows how the brass frame is aligned, soldered, and gradually turned into the skeleton that holds the PCB, motors, battery, radar, and OLED display.

Seven rods are soldered first. The final rod is left out until the OLED is installed, because it passes between the OLED ribbon cable and its small PCB.

It is a slightly awkward way to build a desktop robot, but the exposed brass structure is a large part of what gives TongDou his character.