My other 3D printed products have arrived! One is the Cubichain bracelet (12 mm).
It's surprisingly light and flexible. I like how it shows off 3D printing (it would be very hard to make using conventional methods).
Unfortunately, it was too short when it first arrived. The length you specify seems to refer to the middle of the bracelet, not the inner diameter. I read about people correcting problems with their 3D printed models by dipping them in hot water, then bending them, so I wondered if it would work with White Strong and Flexible (WSF). WSF is supposed to be dishwasher safe, so it should be ok in hot water.
Fortunately, I had access to a kettle that could maintain water at several temperatures. I tried 80C at first, but it didn't soften enough so I changed to 90C. Even at that temperature, WSF is very strong. I was using almost my full strength to stretch the bracelet. Some people say to only dip it in for a few seconds, but I think they are referring to one of the Detail materials, which soften at 80C. I just left it in the hot water for 30 seconds or more. The dye will run from the material, so I used a disposable cup. The water will cool down after dipping it in a few times, so you have to keep changing it.
In the end, the bracelet stretched by about 10%, making it just long enough to put on. The cubes are slightly deformed though. I think it can stretch up to 20% before breaking. I guess the advantage of this method is you get a bracelet that's just big enough to put on.