These center caps are designed to fit Generation II Prius (2004-2009) 15 inch wheels. These are based on precise measurements of Toyota part #42603-52030.
This has the peace symbol embossed in the top of the wheel cap.
Also fits Yaris, Vios
Nylon is NOT UV stable. For maximum longevity and downright good looks, you will want to paint this object. Acrylic paints with a glossy topcoat are a proven method of painting objects printed using Selective Laser Sintering.
Shapeways has a tutorial here: http://www.shapeways.com/tutorials/painting3dprintedsls
And a blog entry here: http://www.shapeways.com/blog/archives/129-painting-your-3d-printed-models.html
Further, you can locate the recommended Tamiya paints here:
THIS DESIGN HAS NOT BEEN CONFIRMED TO FIT GEN II PRIUS WHEELS UNTIL THIS DISCLAIMER IS REMOVED.