That works good Pearly. Kind of like the old sign painter trick for doin layout lines on a sign board with a yardstick and pencil. Even used a pin striping brush with a yardstick run along the edge like that. Here's my crude marking guage I threw together in a few minutes. Only takes one hand holdin the bow and the other the guage. Wedge on one side of the pencil is 1/2", wedge on the other side gives me 5/8". Round dowel follows all the humps and bums great.