Help on clay modeling/molding intricate parts

I had posted this on another forum asking for advice as well, but I haven't received a reply in days and I figured that the community there was more into the artistic craft sort of stuff. I like the engineering mindset of this community far better as I tour around here a lot looking at neat instructables, so maybe you guys can offer me some solid advice.

I have a series of small metal parts with minute details on them, and I want to take them and create clay replicas of them. I want these clay replicas to essentially be spot-on accurate to the original and be durable; not brittle, heavy, and perhaps slightly flexible.

Essentially, though it may sound strange, I'm working on a World War II movie project. I don't have the fire-arms necessary for it, and I don't have a reason to use real fire-arms, so I want to create dummy replicas that have believably working systems that of course are just made of clay and aren't capable of firing. I'm also of course going to create miscellaneous objects, such as papier mache helmets and whatnot.

At the bottom are a few examples of what I need constructed.

I don't know what type of clay would be the best for this; I can afford to have it be slightly flexible, but not rubbery. It would be handled and roughed around a lot and couldn't be brittle, lest it shatter. I also think that I would probably have to make a mold of the metal parts, but what material should I use? Some sort of molding latex, or clay? Would the clay stick to the metal, and if so, can I oil the metal to make it easy to remove, or would that interfere with the chemistry of the clay somehow?

I've also considered maybe using papier mache to mold the parts, as I'm sure that it would be tough. Perhaps I could achieve this by carefully cutting the strips? I've considered that clay may not even be the best material for this, although it may certainly help with molds; tutorials on how to create molds for complex objects are also appreciated, since these have internal chambers and whatnot. Maybe I can eyeball it and cut the parts out of foam, and then coat it with some sort of hardening resin?

I don't know, I'm certainly up for suggestions here.

Thanks in advance!

P.S. Oh, by the way, if any moderators feel that it would be better suited in the "Burning Questions" subforum feel free to move it there; I wasn't sure whether or not to post there since I simply want advice, not someone to make an instructable for me.

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caitlinsdad7 years ago
https://www.instructables.com/id/Making-an-army-of-Gromits-Claymation-Mold-making/
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Also look up jewelry casting or prop molding.  Techniques are similar.  If you need life-size weapon props for movies, you don't need super-fine detail unless you go for a close up.  Look at some of gmjhowe's instructables on how to create weapon replica's - although his are cyberpunk - you can get the idea of using ordinary stuff and cardboard and dry-brush paint to simulate metal.

Look up indymogul's various videos on props and cheap moviemaking.  Good luck.
I would make molds from silicone RTV mold maker, and make my parts from polymer clay of some sort. Once baked it sometimes remains slightly flexible, but it will take a coat of spraypaint (which would replicate the metallic finish).