Day 3 I went with tubes and wires, partly just to see how much I can dedicate myself to drawing a shit ton of wires and what I found was I enjoyed drawing them lol. Vacuum tubes are in particular a thing I'm interested in drawing since you see them attached to gas masks sometimes and gestures to my username**remembers people misread it as ghost mask ghstmsk<ghastmask<ghast + gas mask.
Also I did some hatching practice on this because I was analyzing the styles of gachiakuta, soul eater, and another artist i like chupabara and went "i should do more hatching".