Check out http://www.ganoksin.com/gnkurl/1bo
They have a material that you can have 3D printed called Alumide.
This stuff can be heated to over 300 degrees F, this way you can make
vulcanized molds straight from the 3D printed copy. The minimum line
thickness for alumide is 0.7mm
If you prefer a metal master… You can also use polymide, which is
supposed to burnout clean, it just requires a longer burn out time.
The minimum line thickness for polymide is 0.3mm (if memory serves).
Shapeways also offers casting services, they will cast polymide in
silver, but the investing fee for one piece is $40+the cost of the
You can also get 3D printed stainless steel, but the minimum line
thickness is 3mm.
Their prices are decent as well, small polymide models usually cost
a couple of dollars and alumide is slightly more. They do have a
minimum of $25.
I hope this helps