There are many customizable bracelets on Thingiverse. Here is another! I was inspired by Emmett's Stretchy Bracelet design; I made one and was impressed by how flexible it was, even printed in PLA.
With this customizer, you set the basic bracelet dimensions - inner (wrist) diameter, thickness, etc, then fiddle with various settings to control the compound shape of a cutout that is stamped out of the periphery to form the "ruffle". These bracelets get their flexibility from packing many folds into a small band - a bit of flex in each corner adds up.
Output is a solid model intended to be printed with no infill and no top or bottom layers. Warning: the customizer does not prevent you from creating unprintable designs, so be careful to avoid floating fragments or intersecting ruffle patterns.
I printed the
rufflebracelet-1.stl sample in brown PLA on my Printrbot Simple and gave it to a friend for her birthday. 0.15 mm layer height, no top or bottom layers, no infill.