Not knowing the size or shape of you product I will offer a few suggestions. You mention castings. Depending on your part and the amount you plan to make, Urethane castings may work well. My suggestion is to go to
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Out of 4 sources for this they are the least expensive and do the best quality work. Ask for Faye. She will get you to where you need to go. As for objet that people speak of, your system is an enclosure right? If you have any heat in that enclosure you need to be careful because the Objet melt point is very low. Like 110-120 degrees F. I use C-Ideas for this
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They also have FDM and SLA machines as well and will be happy to give you all their wisdom. Ask for Dan. Those two sources are the best I have and they know all. Call and pick their brain. Thats the best advice I can give.
Ken M Muderlak Design