Profile gauges are indispensable when you need to copy an existing profile or molding. A row of fine stainless steel pins held snugly in a steel frame conforms to whatever you press it against, holding the shape while you trace it onto stock. The 150 mm gauge uses 0.8 mm pins and captures profiles up to 2 in deep; the 300 mm gauge uses 1 mm pins and reaches 5-1/8 in deep for big crown, casings, and timber profiles.
Steel pins produce much smoother curves and finer detail than the plastic gauges sold everywhere else, and they do not sag or take a set.