How to make some emergency eyeglasses. Useful little tip, no?
These emergency glasses are designed to restore a bit of your sight by working on the principle of the pinhole camera. The pinhole captures only certain straight rays of light that focus on the retina of the eye (or on the film plane of a pinhole camera). Align several of these pin holes onto an opaque surface and look through it, and voila! – each hole becomes a tiny lens offering a clearer image.