Useful paper
A windowsill instrument
Northern hemisphere edition

Make a paper sundial

A little borrowed sun.

True northA day, drawn by light.Horizontal dial / latitude 45° N
06:00Noon18:00

The hour-line geometry is for a horizontal sundial. Shadow length is an equinox illustration; it changes with the season. Print the dial and gnomon together at 100%, then cut and fold.

Paper sundial. Point the noon line to true north. Use a level base. Read solar time, not civil time.

Fold this tab under45°

One triangle.
One useful shadow.

Cut the solid outline. Fold the tab beneath the triangle and attach it to the dial along the noon line, with the pointed end at the center and the tall end toward north. The sloped edge is the timekeeper.