One empty can of an energy drink with one hole on its side and one photo paper.
I’ve been to an AstroCamp in TarjÃ¡n, Hungary last summer. There were two amateur astronomers, who gave me three handmade so called solargraphs, which they made themsleves.
These particular ones are made of energy drink can, cut half and a photo paper inserted inside the can. Then taped together, made a pinhole on the side of the can opposite where the paper placed and kept it outdoors on my balcony at a fix place for a little longer then a month (between 23.12.2016 – 27.01.2017).
Over a month the arc of Sun – those bright orangy curves – seems to become steeper and steeper, leaving parallel curves on the photo paper. As we approach spring and summer, Sun will appear at an increasingly higher elevation above the horizon, warming the planet quicker as sunlight comes from a more direct angle.