Here's what the other Todd (Todd Boyce of NinjaMagic) emailed me:
"If you're intending to mold and cast this part, a raw output won't be very useful to you for three reasons.
1) The parts my machine creates are very fragile, and will shatter if dropped. This is not as much of a concern for this particular piece since it doesn't have any flimsy parts, but you will still have to be careful handling it. Details like the rivets can break off just by rubbing a finger across them. It will be much more fragile than the parts you got from the Viper.
2) They can not be vulcanized except at a low temperature and even then they will likely distort under pressure. I've done fairly extensive testing and the results are not pretty.
3) The parts may leach a substance which interferes with the curing of silicone molds. It can be done I've heard, you just need to let the parts "dry" for a week or two before trying. If it doesn't work though, you're screwed. Also, there is a chance that small details like the rivets could break off when extracted from the mold possibly giving you only one shot to get a good cavity.
> But how does one perform an investment cast in bronze?
Investment casting (aka lost wax casting) is a jewelry process where a sprue is attached to the part and it is then dropped into a metal flask filled with a ceramic or plaster-like slurry. The slurry hardens and encases the object to be cast.
Then it is put into a kiln and heated to a couple of thousand degrees which vaporizes the model and the sprue leaving a hollow cavity. This is why it is called an "investment" - because you're destroying the original as an investment for a more valuable metal copy.
Metal is poured into the cavity and when cooled, the mold is shattered and the perfect metal copy is extracted. In jewelry, the metal used is typically silver or gold, but bronze is better for our purposes. It is very cheap, it results in very clean investment casts, and it plays nice with vulcanizing molds.
Also a metal master won't ever be destroyed or damaged in the moldmaking process so you can always make new molds off of it if you change casters, or need a new master mold.
Trust me when I say that the only time you should ever order a raw prototype from me is when you know that you're going to make adjustments and it is simply to do a visual check to make sure the scale of details is right, or to test-fit parts.
Or to check the quality of my output of course.
After dealing with this stuff for 3+ years, I can't stress the importance enough of having durable metal masters.
I do have to do prep work to a model if it is intended for investment casting (I have to add what I call a "sprue hardpoint" to the part) because otherwise proper clean-up on the part is pretty much impossible.
So, if I run a raw output without the intent for investment casting, understand that you can't change your mind once I launch the job on the machine."
