STL file: http://www.geekhaus.com/makerhome/day132_stretchybands.stl (but customize your own!)
Thingiverse link: http://www.thingiverse.com/make:61047
Settings: MakerWare .3mm/low on a Replicator 2, very fast to print.
Technical notes: The file above is for a 50mm interior diameter, which is about right for a typical 7-year-old girl. To make the stripes, we colored the filament with sharpie before it went into the extruder. There was some weirdness for the thin .4mm thickness, with a few parts of the model printing in two shells instead of one, but .3mm thickness was causing gaps in the model. Experiment in the Customizer to find the settings that work for you, but here are the ones that worked the best for us (makes the first two bracelets in the picture):
insideDiameter = 50
thickness = .4
resolution = 60
radialCount = 15
outsideDiameter = 64
height = 6
