That's a terrific story Borate! I don't think they allow prosthetics of any kind in the Para-Olympics in swimming (yet), but I don't know all of the classes of swimmers. But I hope they allow these into classes, or perhaps create new classes of swimmers that wear them for their events.
3d printers have been around for many years, actually almost 3 decades. But it's now at a point where almost anyone or small organization can afford. And what a great use to help those missing limbs have the ability to compete at the highest level of all sports - great stuff!