This article describes the "XY method", a practical process for marking time divisions on sundials. It details how to calculate shadow angles from first principles for various dial types and then plot them directly along rectangular borders using a graduated straightedge, acting as an "Add-on" to computer design programs. The method was adapted for complex declining/proclining dials and can also be applied to circular or octagonal dials.
Dialling Tools,
Mathematics of Dialling,
Sundial Design & Layout