Choose a flat, level surface with full sunlight
Find your local latitude
Cut a flat base from wood, cardboard, stone, or plastic
Mark the center point on the base
Make a gnomon from a straight stick, triangle, or metal strip
Set the gnomon at an angle equal to your latitude
Attach the gnomon firmly at the center point
Align the gnomon to point true north in the Northern Hemisphere or true south in the Southern Hemisphere
Use a compass and correct for magnetic declination if needed
Place the sundial in its final outdoor position
Wait for a sunny day
Mark the shadow tip of the gnomon at each hour
Label each shadow mark with the correct time
Adjust the hour marks for your location and daylight saving time if desired
Test the sundial on different days and refine the markings
Seal or protect the materials if the sundial will stay outdoors