Blender Cookie explains how to prepare your models for 3D printing at Shapeways, and they offer a 15% discount on any orders, valid through February 19th.
Jonathan Williamson writes:
3D printing continues to get better and cheaper every day. It also is becoming more accessible to casual users and artists. One of the great services offering 3D Printing to you and I is Shapeways. Shapeways allows you to not only get your models printed, it allows you to create an online shop to sell your own models. It’s like the Etsy of 3D printing.
Note: I work for Shapeways and helped Jonathan prepare this tutorial.