Questions about making molds

Hey all. So my suit is coming along nicely and I started thinking about perhaps making molds to rotocast resin parts. (this is no time soon! Just thinking about it.)
So I was watching James's videos on his YouTube channel. (more details at xrobots.co.uk ) in a comment on the video he said he used approx 45-50 kg of silicon rtv to make his molds. Maybe I'm doing my math wrong. But I get that that equates to 1763 oz. or about 13 gallons.
I'm finding that To buy silicon it's around $100 a gallon... That's $1300 for the silicon to mold iron man!! x_x
Is this about right? Did I do math wrong? Or am I just not finding the right supplier?
Thanks. And btw, James, your tutorials are amazing and very appriciated!

Yes I estimated about 800 GBP at retail cost in 5Kg containers... although I've taken nearly 18 months to get anywhere near having moulded the whole thing, so that's only ~£45/month ;-)

Each leg mould piece was 5Kg, so that's 20Kg just for the legs, excluding the feet.

...which is $1236... Wow. Haha thanks James.
Plus fiberglass plus resin... That is no small investment to make molds!

I found it actually a little higher than that number but I have about 20% more pieces than most make for a suit.
In your calc you forgot all the time as well as the mold jacket material and the small stuff like gloves, cups paint brushes etc it all adds up. In the end it really is far cheaper to save up and buy if your able to. Or stay with the pep version and have a one off.

Or make copies for people who are about the same size as you to help offset the costs.

Sent from my Apple Newton

Yes that is also an optioin for sure.
But it is a huge amount of work and time if you go down that path as I know first hand, just be prepared to devote a lot of time to the project in that instance.

NormanF said:

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Or make copies for people who are about the same size as you to help offset the costs.

Sent from my Apple Newton

Although Silicone is better, being flexible, it is actually possible to make rigid moulds out of fiberglass, providing you have a lot of release wax in there and there aren't too any undercuts, and you use lots of pieces to the mould so you can actually get it off the original and the cast.

Here's an example of some Fiberglass only moulds:

Dome
Centre Foot

...but I'd still rather use silicone from the point of view of ease.

Yes figerglass molds can be used but you have to plan them well so there are no undercuts which usually means 3-4 part molds.
They do work exceptionaly well for runnign Urethane or silicone in though, I have quit a few Glass molds we use to run Batman armor and the rubber pieces for Ironman. They will last way longer than a silicone mold and about 30% the weight.

If the original is foam then you could make plaster moulds, destroy the original pieces to get them out of the plaster. Then with a LOT of sealing inside the mould and lots of release wax you could make a rigid cast in the plaster mould, then smash the mould to pieces to get the cast out ;-)