>>8400729You'll never really get a show accurate one that won't be a mess somehow. He's a weird marshmallow boxman, with no real discernable joints, who also has giant shoulder pauldrons that would block his arm motion just about any way you could think of. On top of that, he has to turn into a big specific jet, something that is mostly rounded and curved surfaces, and a tank, that is fairly angular, and a boxman marshmallow robot.
In short, the best you'll get will be compromised in some way, unless you want a literal statue of his robot form, or something that has to prioritize at most, two of his modes. This is a fate most triplechangers have to share, however, because they all tend to have innately conflicting designs. Honestly the easiest to do is probably Astrotrain, and mostly because both the train and the shuttle mode are reasonably able to be "a tube", and then just trying to fit in the appropriate bits for each mode and store them somewhere.