The Nasus Saga: Molding & Casting Gems

Since the lights were complete, it was time to mold and cast the gems I would need for the armor.  At this point, I had pretty much already patterned out the pieces of the costume that would need the gems, so I knew what shapes and sizes I needed to make.

I used some Plastilina clay, which doesn’t harden, to sculpt the pieces I wanted.  I started with a diamond for the skirt piece, then made a slightly elongated pentagon for the chest piece.  I ultimately used a small half sphere cake pan as the base for a mold to do the gem for the axe.

Let me mention here that I had some failures at this at first.  My initial molds were sloppy and made of silicone.  I’ll spare you the details, but because of that sloppiness, and because I had some Instamorph, I decided to try using it for the mold on my second go round.  And I stupidly decided to use the cake pan as a direct mold for the sphere.

This is the resin I used to fill the molds.  And here is the first casting attempt, with the second set of molds.


The Instamorph stuff is neat.  When it first comes out of the boiling water, it is clear, like this.  Then it turns white again when it hardens (see picture above).

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However, I discovered that despite using a mold release spray, that these materials are too hard to use when the material you are casting in them is also hard.  The cake pan will forever have that resin in it.  I might try to find some metal cutters an cut the ends off of it so I can still use the unruined part.

I did manage to get the diamond cast out of the plastic.  But I did so by remelting it, and slowly peeling off as much of it as I could, only partially burninating my fingers during the process.

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It was an interesting removal process as I had placed my lights into the mold during the curing process (around 2.5 hours in seems like a good time to place them in if you are curious) so that they would get stuck in there nice and permanently.  Here is all the plastic I pulled off of the gem after it was set.

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It worked out okay, but I will probably hope that people do not look super closely at this gem on my armor hah.  There is still a bit of plastic on it, which makes it a little cloudy.  I did spray some Acrylic sealer on it to try to bring back the shiny clear state, but it didn’t completely fix it.

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The other two gems had to be remolded and recast.  I bought some more silicone putty at Michael’s since the hard molds worked so poorly.  Here they are in the molds, pre-light drop-in.

IMG_0998In case you are curious, this resin has a lot of bubbles in it when you first pour it, and they release after a few minutes in the mold, like the pentagon.  The half sphere was poured second, and right before this picture was taken.  And this (see below) is what my table looked like while the resin cured.  When I dropped in the lights, I used string on the chandelier to hold the lights up a bit and prevent them from moving / tipping into the resin goo.


This worked well for the half sphere, but I had some issues with the lights moving and falling over in the pentagon one, despite my best efforts.  Here are the final gems.  The pentagon lighting is a bit wonky because of the way the lights fell over in the resin – see how the bottom half is a bit dark?  Hopefully it won’t matter a ton, but we’ll see when I get the gems onto the armor!

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