The midterm exam for our daughter’s freshman geometry class is to make a mathematical instrument. She chose this traveller’s sundial (Equinoctial Dial) originally designed by an English mathematician, William Oughtred, in the early 17th century.

And it works! Adjust the center slider to the time of year. Point the device to true north along your latitude and it will tell you the time. Or, as our daughter pointed out, if you already know the time, you can use it to find your latitude.

She used proofgrade draft board to cut all the pieces. Hinged with brads, aluminum can slider (not cut with the forge).

Thank you Glowforge!