On the old forums, there was someone that found a company that would do it for a reasonable price.
I used to work with guys that did stereolithography work at a US Navy engineering lab. It is sort of a 3D printer. You have a tub filled with liquid that turns to a solid when hit with a laser. The laser makes the image by drawing the object on the surface of the liquid. There is a base plate that lowers after a layer is completed, to allow the laser to “build” the next slice of the object. It depends on the precision desired, but usually the layers were in the .003-.005 inch dimension. When the process is finished, you have an object that is a solid resin. There are different resins for different purposes. For prototypes, they would scale the object as actual size. It was pretty strong plastic, maybe slightly more brittle and yellowish/gold in color. It could be painted or glued. Another option was to make slight changes to the scale. The end object could be used to make casting molds. The exact scaling depended on the type of casting. An quick reaction method was to adjust the scale and create the object with a lot of air holes in it. The end result was much lighter. The advantage was that the object would be used as a direct mold. Just put the form around it and pour in molten metal. The metal would dissolve the object and you had a 1-time use mold.
You might want to check some CAD/CAM businesses or universities that have the equipment.
Back to the original, if you use the stereolithography to make a mold, the end result can be any material–steel, aluminum, plastic, rubber, etc.