When I build a car the answer is liftarms and I love them because his light weight and soft curves, but when I build a machine or a truck everything changes and my MOCs loose quality although they have many features or qualities. I always look for maximum functionality sacrificing aesthetics a bit but the question is, do I have to use bricks in machines and trucks?, I wonder if the weight gain would be significant. For me a hybrid structure is always the best, talking about machine arms for example.