I made this 2001, during a fit of creative insanity. Just make sure that all the safety pins are the same size, and the beads will slide all the way down the open side of a safety pin.
String the pin with beads, close, and repeat with the rest of the safety pins. My bracelet contains about 40 - 50 pins, make as many as will comfortably fit your wrist.
To connect, thread an elastic string through the little hole at the bottom of all the pins (make sure the pins line up and are all facing the same way - this is important!). Tie off. Do the same for the hole at the other end of the safety pins. Although to be honest, I used 2 cheap hair ties, and it's lasted me this long. Use whatever works for you!
Wear it. Love it. And keep an eye out for rebellious pins - they'll occasionally pop open.