While people are commenting that $30 in materials is not very realistic, I find that's nothing compared to stating that 2 people can build this in 4 hours. I don't think it could be built in that amount of time if you used a large cnc router and had all the G-code already prepared. Looks to me like a week of work. I love the animations. Also the chain drive going around the bicycle rim is downright silly, you would have to weld gear teeth on the rim which would be extremely difficult.