Sign Foam Modelling: Car Sketches

I’ve been getting comfortable in the gatech machine shop, and between coats of primer or spackle on models for class, I turned some sign foam scraps into these new forms. I was hoping that I could get some input on finishing these or tips for starting over next time I’m bored in there! I’m nervous about attempting symmetry after sculpting just the one side of a car, and am not aware of any good techniques for making it work other than maybe paper templates/calipers/estimation. Let me know what you think.
(The one top/front view that is symmetrical is a photo-chop)