[Ponoko]
[Philip Lelyveld comment: this gives you a sense of materials costs for 3D printers]
Been looking for a way to test out your larger 3D designs without having it cost a fortune? We have just added White Plaster to our materials catalogue and your 3D product can be made for as low as $.69 a cubic centimeter!*
Because of this low price, white plaster is a great material to evaluate the aesthetics of your larger design before committing to a more expensive material.
See the material page for all the details and design specs.
See the full post here: http://blog.ponoko.com/2012/05/24/new-material-for-3d-printing-white-plaster/