you can now 3d print, promote and sell your product in one place

Shapeways.com is the place that can do all that for you. you can create your own designer profile on shapeways, you then upload your design to shapeways, their designers then check if your design is 3d printable. Then you get an estimate of how much the production of your product will cost, to which you add your own valued price. The great thing is, that you don't need to invest money into production, you basically pay for the first 3d printed design to check it for quality etc., customers can browse your designer profile on shapeways and order your designs, shapeways will 3d print them and charge them for the price you're asking, deduct the basic production cost from it and the rest goes into your pocket. It's brilliant, especially for young and starting designers and a nice way to test out your design.
They can do 3d print in:
plated gold
antique bronze
stainless steel
glass
plastic
alumide
etc.

CHECK IT OUT @ SHAPEWAYS