You are likely aware that a total solar eclipse will be viewable in the United States on April 8, but in this case, "viewable" does not mean you can watch it with a naked eye. Staring directly at the sun can cause blindness, of course, but there are ways to safely watch (and photograph) the eclipse.
Let's get clear on things you cannot use to watch the eclipse: Sunglasses are out, as are 3D movie glasses (what are you thinking?!) and binoculars. We have a guide to choosing the right eclipse glasses, but if you don't have them yet, it's too late at this point.
But don't despair; you can make a pinhole camera from easily obtainable items. There are a few kinds of pinhole cameras, some made with boxes and cylindrical containers, but you can also make do with two sheets of card stock or paper. Let's start there.
Getting Started
Get two pieces of card stock (the kind that you used for projects in grade school) or plain paper. Just know that if you go with paper, your camera will be far flimsier. Then get either a sewing needle, paper clip, or thumbtack.
Take one sheet of your paper or card stock and make a small round hole right in the middle of it with the sharp object of your choice from the list above. Or, if you have aluminum foil, cut a small square in the middle of the piece of paper, tape over it with aluminum foil, and make a small hole in the foil.
Viewing
Before the eclipse, take out your pierced piece of card stock or paper. Put the plain piece on the ground. Stand with your back to the sun and hold the card stock or paper with the hole in it above your shoulder so that the sun shines through it and projects onto the plain piece on the ground. Look at the piece of card stock or paper that is on the ground during the eclipse.
You can adjust the size of the image by moving the card stock or paper that is over your shoulder closer or further away from the piece on the ground. Closer makes the image smaller and further away makes it larger. Is it a little like Plato's cave in that you're experiencing a shadow of the thing and not the thing itself? Yes, but you will not be blind, so there's that.
If you're feeling more ambitious and happen to have just finished up some cereal, you can also make a pinhole projector box; check out the instructions in NASA's video below: