They don't use wood either, somemodelers use card stock (or something similar), I've seen this one before and don't remember off hand everything he used, but I'm pretty sure it just wasn't simple grey plastic. Also, it is written in the description that it is scratch built (how many companies make a carrier that big?).
Either way, it's not easy to make a seamless model without paint, in any scale.
P.S. I built the enterprise in 1/350 scale, the paint looks far different from normal plastic. Plastic has a dull shine to it.