Starting the summer preceding my senior year of high school, I set out on the incredibly long and difficult project of building my own car - a 1974 MGB GT that I had purchased in boxes off of Ebay. The project would take me hundreds of man hours and would teach me tons about mechanical systems, hands-on tools, and intense project research. However, I think the end result was worth it :)
This is the car before I bought it - it had been completely disassembled twenty years prior and left to sit. Time and rust had not been very nice to the frame