My weakness ......I can`t seem to take my time......I get so into the build that I just keep going and going......I just want to get it done so I can start the next one........and my lack of knowledge when it comes to car engines.......I really don`t know that much about them......but,I can pretty much copy a picture of an engine if I have good photo`s.......I probably could read book`s and learn about engines but,again I guess it`s not that important to me.