The Pi Bracelet is made up of 9 interlocking links, each with a couple of digits of Pi on it - a total of 14 digits after the decimal (3.14159265358979) and one link with the Pi symbol. Each link is approx 16mm square not including the linkage - and the complete set of links, when connected as bracelet, measures approx 215mm long - fitting an adult average wrist pretty well. Links can be left off to make the design smaller. The whole design can be scaled down to make it work better on kids' wrists. The image shows an 80% and 100% version.
Link Design: The links connect using a custom design which makes it mostly easy to connect, but harder to fall apart. To connect the links, you put them at a 90 degree angle to one another, with the male/pin portion under the female/mortise portion - pushing the pin into the mortise and then straightening the pair until they click in. Separate using the opposite motion. There is often some brim material on the bottom of the model which needs to be worn down before the connection can be made easily - but this actually helps to keep the connection firm and secure.
It might take some connecting and un-connecting to make the pairs of links move and flex freely to lay comfortably on your wrist.
If there is ever a price for this model, 100% of the proceeds will be donated to a DonorsChoose project for educational recipients.