we have a vac-form machine here at my work. next couple weeks i'll try to make a mold of the head lights. but wouldn't forming over the stock light make a negitive mold that is 1/8" bigger (all the way around) than the stock light. then cutting the stock light the new mold wouldn't fit. so you would have to (inside the new neg mold) whatever the thickness of the material your using, line the inside with that. then when you pull the new mold of the "smaller" one, it will fit the stock housing perfect! did i loose anyone?
let me know if i've missed something.