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I just made several sandbags out of Sclupey clay but the process is time consuming. I want to make several structures out of brick or sandbags so I will need a lot. I just bought this molding kit cause it was recommened on here and was highly rated:

http://www.coolminiornot.com/shop/tools-and-misc/instant-mold.html


What materials do I use in the mold? I was thinking of using the Sculpey that I have cause its cheap and very easy to work with but it only cures in an oven and I may ruin it while I'm pulling it out of the mold. I'd rather not drop a lot of money on green stuff. What about resin? I see it at hobby lobby. Will it work in this mold? Is it more expensive than green stuff? Thank you in advance.

FYI, I am sculpting my sandbags and bricks individualy to assemble large terrain pieces and as accents to other terrain pieces. All my molds will be made of my sculpts (easy stuff like sandbags and bricks) and not anyone's IP.

It may depend on whether the silicone can take the heat of curing resin. Have you considered plaster of paris? There are a few different types including one called rockcrete that are tougher than normal plaster. If you are just going to make buildings etc,plaster may well be the cheapest way to go and you do get a lot for your money.

The mold will not beable to take the heat of an over. I was just gonna squeeze the clay into the mold and pull it out then cure. I've used plaster of paris before but not for terrain. I'll look into it. Thanks for the feedback.

I don't think that you can get the clay out without damaging it. What i do is use milliput + GS mix. Milliput is really cheap and cures when mixed similar to greenstuff - just harder. But the problem here is that you have to wait for it to cure so each cast takes time.

And i'm not so sure if instand mold will be able to endure the heat of cureing resin. One or two casts might work but i fear the the heat will distend the instant mold and you'll lose the mold details quite fast.

How many different molds do you need? If you need a few of those maybe try out true resin casting with silicone molds. Smooth On makes a decent priced starter kit. Depending on what you want to spent and how many molds/casts you need it might be an aceptable solution. http://www.smooth-on.com/Getting-Started-Po/c4_1217/index.html
This will be much faster than epoxy putty press molds because once you have the mold made you can demold the resin parts after 10-15 minutes.

Instant mold goes soft when heated, so no, not suitable for resin curing, unless there is some black magic cold curing resin I'm not aware of.

It is essentially useful for making press molds for stuff, or replicating textures for bases or stuff like that.

I guess you could make a two piece press mold for gs, but getting the halves to line up would be tricky.

You don't have to worry too much about GS sticking, as it is specifically designed not to. That said, a little lubricant is a good idea, just in case.

I do a LOT of scratching building and casting, and have tried many products - instant mold being one of them.

It is NOT suitable for making large numbers of the same item - it is best for a single duplication of a small part (or maybe two).

If you want to get into casting, it can be a lot of fun, but has quite a bit of overhead and is kind of an art (i.e. a lot of it is experience).

If you are wanting molds for bricks, I would suggest hirst arts, I use them for a lot of my terrain accessories.

Again, I am NOT being critical of instant-mold, I use it, many people use it, and its a great product for what it is - re-usable mold material for low volume pulls.

Check out hirst arts molds:
http://www.hirstarts.com/molds/moldsfield.html

and
http://www.hirstarts.com/molds/moldscast.html

best of luck!

 btldoomhammer wrote:
I don't think that you can get the clay out without damaging it. What i do is use milliput + GS mix. Milliput is really cheap and cures when mixed similar to greenstuff - just harder. But the problem here is that you have to wait for it to cure so each cast takes time.

And i'm not so sure if instand mold will be able to endure the heat of cureing resin. One or two casts might work but i fear the the heat will distend the instant mold and you'll lose the mold details quite fast.

How many different molds do you need? If you need a few of those maybe try out true resin casting with silicone molds. Smooth On makes a decent priced starter kit. Depending on what you want to spent and how many molds/casts you need it might be an aceptable solution. http://www.smooth-on.com/Getting-Started-Po/c4_1217/index.html
This will be much faster than epoxy putty press molds because once you have the mold made you can demold the resin parts after 10-15 minutes.

You have to heat plaster of paris? I thought youI just mixed it with water and dumped it into the mold.

I saw Hirst's stuff but I wasn't sure of the scale of the bricks and sanbags.

 Davespil wrote:

 btldoomhammer wrote:
I don't think that you can get the clay out without damaging it. What i do is use milliput + GS mix. Milliput is really cheap and cures when mixed similar to greenstuff - just harder. But the problem here is that you have to wait for it to cure so each cast takes time.

And i'm not so sure if instand mold will be able to endure the heat of cureing resin. One or two casts might work but i fear the the heat will distend the instant mold and you'll lose the mold details quite fast.

How many different molds do you need? If you need a few of those maybe try out true resin casting with silicone molds. Smooth On makes a decent priced starter kit. Depending on what you want to spent and how many molds/casts you need it might be an aceptable solution. http://www.smooth-on.com/Getting-Started-Po/c4_1217/index.html
This will be much faster than epoxy putty press molds because once you have the mold made you can demold the resin parts after 10-15 minutes.

You have to heat plaster of paris? I thought youI just mixed it with water and dumped it into the mold.

I saw Hirst's stuff but I wasn't sure of the scale of the bricks and sanbags.

the plaster (there are many kinds - check the articles at hirst arts) gets hot while it cures, it is a chemical reaction.
Resin gets hot as well as it cures, much hotter than the various plasters.

The instant mold is not flexible really when you use it, and for anything other than simple press molds, you need a silicon mold, which will be flexible enough to remove your object.

If you need a lot of sand bags, look at the tamiya sand bag kits, you can usually pick them up at hobby lobby cheap (especially with their coupons) - I know a guy who made an aegis line out of them.

The other option is to just make the bags and bricks out of air dry clay, which is MUCH cheaper and easier to use than sculpy.

I don't want to discourage you from working with molds and casting - like many areas of this hobby, it can be fun and rewarding - but doing any kind of serious casting does indeed have an investment in time and materials, with a slight learning curve to it.

best of luck