Observation window for a pinhole camera

I didn't plan ahead to buy eclipse glasses, and by the time I looked, there were none left. So I built my own pinhole projector using a cardboard tube, aluminum foil, and this screen window template.

Sizing the pinhole: There's a small fitting test included so you can size the radius to match your tube's diameter (measured in millimeters).

You may need to use the online editor to fit your tube radius: https://models.sgenoud.com/posts/pinhole-camera-window/

Note on the template: You'll need to adjust the heights of the circle so it fits entirely within the side of the tube.

Putting it together: Cover one end of the tube tightly with foil and poke a single clean hole in the center. Attach the adjusted screen window template to the other end, and seal any other gaps or seams with foil or tape so light only enters through the pinhole. Add a paper screen in the window.

How to use it: Point the tube toward the sun and adjust its angle until the shadow it casts is as small as possible — that means it's aligned with the sun. Never look through the pinhole directly at the sun; view the projected image on the screen instead.