He has reached the point where he looks at a picture of a Transformer (say, Sunstreaker), then he draws his version of Sunstreaker, and proceeds to build him out of Legos. He is very precise in his building and transforming. It's almost a point of pride for him.
He also enjoys playing that he himself is a Transformer. His current modes are "guy", "box", and "lion".
Here is Eli with some of his Transformers (toys and Legos) all in "guy mode".
The same Transformers in "vehicle mode"; Eli is in "box mode".
Ultra Magnus - drawing by Papa, aka Les Nies and built by Eli (guy mode, front view)
Ultra Magnus - (guy mode, back view - green Legos in place of gray)
Ultra Magnus - (vehicle mode)
I have a feeling we will be enjoying the company of Transformers for many months to come.