I imaginen it'd depend on what exactly you had in mind. But it could be said that anyone who's making a robot transform from, for example, an 18-wheeler is redesigning Optimus Prime. When I said don't copy Transformers, i didn't mean, don't copy the vehicle they transform into... I meant don't copy the robot part. You can do 18-wheelers, volkswagon bugs, jets, etc which are all used in the cartoon. Just don't make your robot look like theirs!