Another version of this hack, with pizza
This isn't the only way to pull off the pinhole projection method, of course. You could achieve the same with items like a pizza box, as Pizza Hut helpfully offered in the video above. Also, with the pizza box method, you can eat pizza beforehand. The instructions are basically the same, if you watch above.
Don't "make your own glasses" unless...
...You've got the right materials. I see you there, Googling for "how to make glasses" at the last minute and whatnot. Unless you have materials that are ISO-compliant, meaning they adhere to a very important standard for staring at the sun, you shouldn't do this and you will probably ruin your vision for life. If you do have proper lens materials, like "Number 14 Welder's Glass or mylar," this guide ain't bad. But seriously, don't mess around if you're not sure.
There's another, very different method...
It's called optical projection, and compared to the pinhole projection method, it actually provides bigger, brighter, and sharper images, according to the AAS. Unlike the pinhole method, it involves making modifications to a telescope, pair of binoculars, or other lens-based viewing system ( as in "optics," yo). We should make it clear that this is really for experienced astronomical observers, because even with modifications, there's a danger that you might damage your device if you aim it at sunlight this bright, or worse, your eyeballs. If you know what you're doing, go to the AAS for more information.
Or try Neil deGrasse Tyson's hack
Now, if you don't have access to a cereal box or a pizza box, you can still pull off a version of this trick. The pinhole projection method just amounts to tiny holes projecting the image of the eclipse onto larger surfaces. To that point, one method the American Astronomical Society offered is taking your hands and, again, with your back to the sun, holding them up in a lattice-like, fingers-criss-crossed pattern over a patch of sidewalk. You'll be able to see the eclipse shine through on the shadows projected onto the sidewalk. You can get the same effect from standing under the leaves of a tree, too. The principles behind the method all hold.
But perhaps the best, easiest last-minute tool, that doesn't require you to build your own simple pinhole projector, is a common spaghetti colander, as Neil deGrasse Tyson pointed out at a talk on Monday:
“If you can’t come here, you can’t go to totality, and you don’t have eclipse glasses, here’s what you do," he said. "Go into your kitchen and get a spaghetti strainer, or colander -- not the mesh, but the kind with holes in it -- and go outside and hold it out over the ground. Each one of those holes will act as pinhole camera and you’ll see hundreds of images of the crescent sun on the ground, and you can watch the eclipse unfold safely.”
No matter what, don't miss it.