FMX - Yes, just ordinary poster board. In the past I have used all sorts of things (corrugated paste board boxes, notepad backs, manila folders, pizza boxes, shoe boxes ). Thin and stiff is the key. Corrugated box material and pizza boxes were the worst - too thick to cut accurately and doesn't bend well. The others are OK, but don't come in big enough pieces for making body panel templates... So, poster board is my usual choice. It's stiff enough for most things yet easy to draw on and cut...