Got one of those Micromaster sets to decorate my cities (that are currently packed away in order to move house). One of those was Hot Rod if he had no mouth.

Took him apart, then primed him.

Parts were primed in black and also grey for the thighs.

Even after priming and sealing (and sanding in a few cases), parts didn't really want to stay painted.

I'm waiting on some insignia stickers to arrive from Aliexpress, then I can give him a big Decepticon insignia right on the front.

He still has no mouth.

 

I bet you could give him a really cute   with a tiny tipped pen

 

Excellent work on this! You could give him mouth if you had a small enough paint brush, or you could even use (and yes I'm being serious when I say this) a cat whisker.

 

That's awesome! Nice job!