Its been several weeks since I machined the 2008 presidential election mold, and being the bum that I am, I haven't done anything with it.
Last night night I mixed up some Smooth-on two part urethane epoxy and poured the urethane into the purple wax positive mold. When the urethane cured, I ended up with the orange negative mold below. The cool thing about using urethane molds is that they are very flexible and thus you can easily remove the final molded parts without damage.
The urethane is also capable of capturing very fine detail. Even the swirl-like milling marks come through.
After the urethane was fully cured (overnight), I poured some hydro-stone plaster into the urethane negative mold. Depending on temperature, the plaster requires about an hour to cure. The plaster/urethane combo is nice because it doesn't require any sort of mold release.
And thus the Mantis V8's first milled/cast part is finally completed!