If you intend to use a lens or pinhole to form an image of the sun remember that the diameter of the sun image is the focal length/focal distance in millimetres divided by 100.

To get a 50mm diameter sun disk you need a 5000mm lens! In practice using a telescope in eyepiece projection mode is the way to go. That's what I'll be doing. And I won't be letting any direct rays from the sun or it's image get into my eyes.