Artistically, this model is fantastic. I love the look and the aesthetic of machine parts coming together into the model. I would not classify this build as challenging as much as I would call it not fully thought out. While building this model, nearly every piece that wasn't a nut/bolt needed adjustment. A couple of the instructions imply that you need to squeeze some parts tighter, but I found that this was needed constantly as the bolts were not long enough to grip any threads without doing so. I also found more than once stripping out a nut because there was very little bolt protruding and no room to squeeze it smaller. I think this concept is great, but honestly going up one size on all of the bolts would probably be a good idea.