Generally, the construction of a sundial, or sundial, requires scientific knowledge and mathematical skills.
The "patience" method used by this app allows anyone, provided they have sufficient patience, to draw a sundial on any flat surface.
A large help section provides all the necessary explanations to proceed.
Those wishing to address the matter more seriously can consult the author's web pages at https://www.sundials.eu
Write to me and tell me what you managed to do!
My address is gian.casalegno@gmail.com