I received a Discoverer telescope as a gift and hadn’t gotten much use out of it. Bausch & Lomb optics, 60mm focal length. 20x-60x. With Venus about to transit the Sun, it seemed an ideal scope to turn into a Sun Gun. Two first-surface mirrors send the image of the Sun onto a screen mounted on the front of the ‘scope. It worked perfectly; about a 3″ diameter image at 20x.
This is what the Sun looked like from the High Line June 5, when it was visible at all. The screen reverses the image; think of it as a third mirror. If you were standing on the other side, and the screen were translucent, it would be as though you were looking through the eyepiece. With the screen intercepting the image, it reverses left to right.
The best view. There were hundreds of people at the event. About a dozen astronomers from aaa.org had set up telescopes. There were only two ten minute periods when the Sun was visible.
A test earlier in the day. The solar image was enlarged on the screen to 50x. The grain is the paper, but it is hard to tell where the paper leaves off and the grain of the Solar surface starts.
https://finkh.wordpress.com/2006/08/01/venus-in-transit-june-8-2004/ for the 2004 transit.