After some advice on casting 3mm thick styrene build.


Active Member

I've been building a blaster on and off for ages, just built the mag housing using 3mm sheet styrene, but it's not going to be that sturdy, so I was going to cast it.

The mag housing is solid towards one end, but essentially like a doopydoos mag housing but with fins sticking out the back.

Any tips on how to tackle this? I've got some vinamold and some silicone, and a bit of polyester resin, no idea how to approach it!

I guess the main issue will be how thin the walls are?

Thanks in advance.


Well-Known Member
Can you take a photo and show us??...not sure what you mean 'fins sticking out the back'

Below are the mag housings I cast for my e11's and the silicone mold I created for them.

You shouldn't have any trouble pouring a silicon mold over your 3mm styrene and then cast in resin.



Active Member
Thanks RogueTrooper,

The fins come from my switch from metal to styrene - I'd already built the mag from aluminium, cut slots in the barrel, fitted it and decided I wasn't happy with it, but thought I'd keep the fins to help the fit and fill the holes.

I made an error in my original post and I actually used 2mm styrene, I think it might hold up as it is because I have put in little parts to reinforce it, but maybe casting it will give me a more solid piece that will stand up to handling better.

Excuse the scrappy state of the mag housing, I mis-measured and have a bit of filling to do!

Your photos are a massive help - I wasn't sure if I needed to make a two part mould and I have no idea how to approach that as everyone seems to do neat looking moulds with key bumps!

Looks like you poured and then carefully cut into it enough to pull the cast piece out?

One last question - just curious what resin you're using?

Thanks again.



Well-Known Member
Two part molds are not hard to do, they just take longer and require a release agent between pouring the second part of the mold. My e11 builds have over 20 molds per blaster. but most of them are small parts so no real need for two part molds. In fact none of them are two part molds.

Silicone isn't very heavy, so you structure at that size should be fine to mold against. Yes, I just molded in a single piece and then cut down to release the part, it works very well and all the parts are cast that way. I cast the entire folding stock in one mold and it works fine.

I use EasyCast resin because it's 1:1 ratio is idiot proof.


Active Member
cool video! like the idea of using the rivet for the front sight.

was just looking at your moulds again - do you box them in when you cast parts?

I got brave and started with mine, totally misjudged the amount of silicone I had, and ran out immediately, so waiting for some more to arrive now!



Well-Known Member
The rivet just seemed to look good and fits well...yes I do box the molds....that's what' s great about silicone and resin, if you run short, you can always go back later and finish and it sticks really well to the partially cast part or the mold.