Making a pinhole
Flatten out a piece of aluminium can and with a needle, ‘drill’ out a small hole. Go slowly and at each stage smooth off the burrs on each side with some very fine emery paper. Drill again after filling until a small very round hole is obtained. The smaller and rounder the better. Do note however that smaller holes do require more exposure and are therefore harder to use, but results do improve.
Then tape this hole to a lens cap or (as seen below) a lens adapter ring. The lens adapter ring is better because the nearer the hole is to the sensor, the wider field of view you get. Also, it is a good idea to black out the inside of the metal hole plate to cut down internal reflections - I used a permanent marker.