The Fitbit Flex is a wonderful movement monitor, a tiny device that captures motion during the day so you know how much you moved, how you slept, and so on. You wear it in a wristband which looks great, but is constructed of three pieces that are glued together. Mine came unglued, so I designed and printed a replacement. UPDATED: The wristband links are joined by profhankd's printable hinge.Open in Customizer. Enter the length (m) that you measure around your wrist. If you like, select how closely you want the links spaced. Print it using an opaque or transparent filament. It looks awesome in the 'smoke grey' and white PLA that I've printed it in. The front is only 0.5mm thick, so I recommend slicing it at 0.2mm or so layer height. Print one box bottom and box top. Cut pieces of felt to fit inside the top and bottom, and glue them into the box bottom and top. Put the band in the box. Give to a friend.