I am really happy we did this Rube Goldberg project. We had some challenges and some easy parts. The hard thing was to come up with the sketch and all the specific parts. We also had trouble making the books fall and to pull the string that pulls a lever that makes a truck drive and then the truck drives into books and the books hit a marble that goes into a marble maze tower and then after the marble hits the power button and the lamp turns on. The challenging part is that if the marble misses hitting the power switch, the whole thing is over. This project was cool because you can actually see the chain reaction.