I am creating a sword for cosplay, and I need the material used to be clear, rigid, and lightweight, and to cure properly in such a thin mould (and can be poured into the mould I have, as I'd prefer to not start an entirely new process, although I'm open to any suggestions).

I have a mould made from a platinum-cure silicone rubber. It's a pretty simple shape with a 3mm thickness.

left, the blade will be made by connecting multiple together. The center: I'm pointing at where ill put the led strip, facing outwards to light up the plastic. right: the mould used
To the left, the blade will be made by connecting multiple together. The center: I'm pointing at where I'll put the LED strip, facing outwards to light up the plastic. To the right: the mould used

I have attempted to use a fast cast urethane resin, with a shore D hardness 72 that is clear.

The material I used is mass sensitive (cures better at a greater volume/thickness), and does not get very rigid since the mould is quite thin.

Are there any other types of plastics I could use that meet my needs?
I can include pictures of the shape I've tried to cast if that would help, or links to the products I've used so far.

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    Those would probably be useful (pictures and links); something else that would probably be useful would be to know what you intend to use it for. – walrus Aug 29 '18 at 8:25
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    Pictures would be helpful. In the meantime, when casting clear resin, the elimination of trapped bubbles is both more important and more difficult. Two techniques for bubble removal involve the use of a vacuum chamber or a blow torch. You will want to check that your mold is itself bubble free and fire proof before trying these techniques respectively. Also, if the tip of your sword is at the bottom of your mold, farthest from the opening where the resin enters, you may have trouble eliminating bubbles using either technique. A horizontal mold layout might yield better results. – Henry Taylor Aug 29 '18 at 11:46
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    Have you tried clear resin? It's clear, transparent, rigid and easily mold-able. I personally use hot glue for smaller items, as it is easy to work with, but I don't know if it'll be a good choice for something as big as a sword. – Bella Swan Jul 3 '19 at 6:30
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    This is a year-old question, so probably overtaken by events. But if the need arises again, I wouldn't try to cast something like this. Even a metal sword is a lot thicker than 3 mm. Plastic that thin will either be very flimsy and flexible, or brittle and easily broken. I would cut the blade from a sheet of something like clear Lexan. Judge the required thickness by how flexible the sheet is. If you're just going to wear it, it can be more flexible than if you intend to wave it around. – fixer1234 Aug 25 '19 at 0:41
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    Very impressive job! It turned out great! – fixer1234 Nov 18 '19 at 1:25

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