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I'm trying to make a 7 inch tall Space Marine, several in fact but I'm new to casting and looking for recommendations on mold-making and casting materials.


So far I hear that Alumilite and Smooth-on are good producers but they offer several versions of each so I don't know which is good for a durable and paintable figure.
The points of reference for these qualities for me are:
- Forge world
and
- the people at Industrial Mechanika ( https://industriamechanika.com/shop/derek-stenning/47-derek-stenning-s-dystopic.html )
I emailed them about the materials, and heard back from FW, but of course with a polite "no", and the other guy didn't respond .

So if anyone can recommend specific materials for or above the quality of said figure companies and an example figure or a good Youtube channel, blog etc, would be greatly appreciated!

I have used a variety and I like the Smooth-On OOMOO 30 silicone for the molds. The only problem with it is that even when tightly sealed, it tends to harden in the bottle if not all used.

A 2 part (2 sides that join together) mold is preferred for something like a marine which has lots of undercuts. The mold will need venting so the air has somewhere to go when the resin is poured. This type of mold will probably use up all of your silicone so getting it right on the first try will be tricky.

For resin, I recommend something with a longer working time. A lot of the resins I have used set within 2 minutes which goes by quick and leaves little time for error.

Before beginning, I suggest practicing on something else first. Use a starter kit like https://www.smooth-on.com/products/pourable-silicone-starter-kit/ or https://www.alumilite.com/store/p/948-Mini-Casting-Kit.aspx

Have a read through this;
https://www.dakkadakka.com/dakkaforum/posts/list/0/307451.page

I work as a caster. I would recommend trying out some of the casting products that are designed to work without pressure or vacuum first, just to get a feel for how the process works. However, you won't get results as good as you would with production-grade materials. This can be fine! If this is intended as a hobby project and you're not making lots of casts, you can substitute time in place of money and equipment - your casts may not come out of the mold as professional-quality pieces, but nearly all the problems this creates can be fixed with putty, sanding and patience. Smooth-On sells starter kit with OOMOO silicon that's designed to be easy to work with without specialized equipment.

If you're being more ambitious, high-quality casts usually require some specialized equipment to produce. The process I use is much like the one used by companies such as Forge World. I use Smooth-On Mold-Max 20 silicone and Smooth-Cast 305 polyurethane resin, and ER200 mold release.

In order to avoid bubbles or voids in your finished product, the resin needs to cure under pressure. This is done using a pressure pot - a sealed vessel that you place filled molds into, then seal and pressurize with an air compressor to about 45-60 PSI. Most are adapted from industrial spray paint tanks. A new one will usually cost about $150-200.

In order to make your own molds, you'll also need a way to de-gas the liquid silicone after it's mixed. This requires a vacuum chamber to pull the trapped air out of the silicone so you have a void-free mold that will work when pressure casting. While these can cost upwards of $300-400, you'll only be using it for a minute or two each time you pour molds. If you're not starting your own casting business, owning your own is usually overkill. See if there are any local manufacturers or maker spaces that might have one you can use.

As a general rule, pick a slower-curing resin (305 is the slowest of the regular 300 series). This gives you more time to work, produces less heat when curing and is gentler on your molds.

You'll want to start out by doing at least a few simpler 1-part molds (parts that end up flat on the back) to build up your experience before tackling a more complex project with 2-part molds. There's lots of great information available online, but a lot of this can only be learned through practice.

Good luck!

Wasteland wrote:I work as a caster. I would recommend trying out some of the casting products that are designed to work without pressure or vacuum first, just to get a feel for how the process works. However, you won't get results as good as you would with production-grade materials. This can be fine! If this is intended as a hobby project and you're not making lots of casts, you can substitute time in place of money and equipment - your casts may not come out of the mold as professional-quality pieces, but nearly all the problems this creates can be fixed with putty, sanding and patience. Smooth-On sells starter kit with OOMOO silicon that's designed to be easy to work with without specialized equipment.

If you're being more ambitious, high-quality casts usually require some specialized equipment to produce. The process I use is much like the one used by companies such as Forge World. I use Smooth-On Mold-Max 20 silicone and Smooth-Cast 305 polyurethane resin, and ER200 mold release.

In order to avoid bubbles or voids in your finished product, the resin needs to cure under pressure. This is done using a pressure pot - a sealed vessel that you place filled molds into, then seal and pressurize with an air compressor to about 45-60 PSI. Most are adapted from industrial spray paint tanks. A new one will usually cost about $150-200.

In order to make your own molds, you'll also need a way to de-gas the liquid silicone after it's mixed. This requires a vacuum chamber to pull the trapped air out of the silicone so you have a void-free mold that will work when pressure casting. While these can cost upwards of $300-400, you'll only be using it for a minute or two each time you pour molds. If you're not starting your own casting business, owning your own is usually overkill. See if there are any local manufacturers or maker spaces that might have one you can use.


As a general rule, pick a slower-curing resin (305 is the slowest of the regular 300 series). This gives you more time to work, produces less heat when curing and is gentler on your molds.

You'll want to start out by doing at least a few simpler 1-part molds (parts that end up flat on the back) to build up your experience before tackling a more complex project with 2-part molds. There's lots of great information available online, but a lot of this can only be learned through practice.

Good luck!

I heard some stuff about evacuation and compression and knew I'd have to find a work around, so thanks for the tips you probably saved me some bubble induced tears.

I'll probably get a starter kit and do one of the thigh segments or something and work my way up.

Thanks to all three of you!