A Trick With Mirrors. Two mirrors, hinged or butted at a 90 degree angle, can help you design your pattern. You set the mirror on the top sheet or stack to see the desired effect you will attain in a 4 piece book & butt match...

After trying several positions, "nail it down" to the one which suits your project. Grab a Square and place it inside & touching the mirrors. Take the mirrors away and mark the top sheet of veneer along the edge of the square - all the way to the edges of the bundle...