Folks: No 'stack of boxes', please, that's way too simple, unless we mean Danbo ^_^; you could reduce a lot of very different-looking designs down to a stack of geometric shapes. The PLEX designs for Machine Robo and such could be described the same way, but their details are very different. I think 'stack of car parts' would be a little better - a lot of G1 toys go from altmode to robot in as few steps as possible. If a large chunk of plane or car makes an acceptable body part - it stays. This seems pretty obvious. The thing I am wondering about is the detail of the robot-only parts. At this point, 30 years later, TFs have influenced many things, and the robot parts just seem like generic mecha. However, compare to the other big 80s stuff, and they don't just look like everything else out there. So what is it that makes a design look like a Transformer?