Holographic projectors can be costly items at the best of times, but with a bit of ingenuity and an old CD case you can make one yourself for your iPhone.

How to make a pinhole projector from a cereal box to safely view the total solar eclipse. You don't need fancy equipment to watch the celestial event.

Supplies There are many ways to make a pinhole projector, but you really just need two things: something with a pinhole in it, and something to project the image on.