Carved corner stencils

Some stencils for laying out carving patterns. This is the traditional method used. Small notches for marking the frame with a pencil, flipping for the opposite side.

Here's one from the Archives of American Art; a Foster Bros. stencil, here. 
2nd. from left at the top.

Another method would employ a chalk bag, pounced on a pounce pattern. The drawing is "traced" with a small wheel, set with sharp pins, perforating the paper. The chalk marks the frame below through the small holes. My method of choice is a computer print, allowing me to rapidly alter dimensions. See the post from 3/11/09, A New Design.