A method that I used quite sucessfully to show off the sun for the transit of Venus back in 2012 was to reflect the sun (from a signal mirror, naturally!) through a large pinhole ( 1/4" = 6 mm, in my case) into a darkened room to project on a white piece of paper at the appropriate distance from the "pinhole" (53.7 ft in this case, though I'm sure I was a couple feet off).

In my case, the image of the sun was 6" diameter with a theoretical image resolution of 1.5 mm. Convection currents made the image ripple a bit, but it was still good enough to show sunspots and Venus, and the 6" diameter image was impressive for the neighbors and their children that I shuttled through.

A (cleaned up as described thereon) photo can be viewed here: 6" diameter image of transit of Venus in 2012

For this round, I'm using a smartphone photo clamp to mount the signal mirror to my tripod for easy adjustment as the sun moves.

For a 1/4 inch ( 6 mm ) diameter hole, WIkipedia says you can get 1.5 mm resolution on a 153 mm wide projected sun images if the spacing from the hole to the projection screen is 54 feet. See: https://en.wikipedia.org/wiki/Pinhole_camera The formula is:
d = 2 * sqrt( f * lambda), where:
d = diameter of the pinhole: 0.006 meters in this case
lambda = the wavelength of the light: 550 x 10^-9 for the middle of the visual band
f = hole to screen distance: 16.36 meters = 53.7 feet, here
s = radius = d/2
resolution = s/2 at optimum distance = d/4 = 1.5 mm here
Projected sun diameter = f/107 = 153 mm here.