The website I visited has instructions on making one of these 'pinhole projectors'... read all the way through the comments to find a helpful tip on sizing the hole. Also in the comments was a simpler method- to use a pair of binoculars backwards...
Here are the instructions.
"Hold a pair of binoculars with the big end pointed toward the Sun. You only need one barrel of the binocs for this, you can leave the lens cover on the other unused barrel.
The binocular will then project an image of the Sun out of the eyepiece. Tape a piece of white copy paper onto a large piece of cardboard and use it as a projection surface for the image coming out the back of the binocular. Experiment with distance from the eyepiece to hold the paper. A foot or two distance between the binoc eyepiece and the projection surface seems to work best for me. Experiment for yourself.
You’ll see what I mean when you try it."
BTW, you do NOT want to look at an eclipse without a special viewing device. Sunglasses don't count, either. You can severely damage your retinas. A funny video that shows what can happen is Brian Regan's "Big Family Stuff", the sun part starts at about 2:58.