The RepRap machine uses polymer extrusion to draw your model, which wouldn't yet work for keys. If it's a good lock, you'd get a couple of uses out of it, but t

The RepRap machine uses polymer extrusion to draw your model, which wouldn't yet work for keys. If it's a good lock, you'd get a couple of uses out of it, but the pins would destroy your key and the torsion would bend it.