Resin Casting – Tips and Tricks

Published on

April 3, 2016

Got a physical object you want to duplicate? Want to make 100 copies of a 3D print, but can’t afford to wait 100 days? Do you want a robust sculpture but don’t have a kiln? Resin casting to the rescue!

Getting started

You will need an item to be duplicated, 2-part silicone for the mold (or mould, depends where you live), mold release spray, 2-part resin and some optional additives. I recommend Oomoo product line, they are easy to use and affordable. My wife ( carved a few really nice sculptures out of soap stone.


I wont go into lots of detail about the process itself, because it’s already explained in a hundred youtube videos. Here is a good one:

I do have a few tip, tricks and warning though. Here they are:

TIP: Lego Mold

The silicone is expensive, if your object is irregular it can be trick to make a mold that conserves material. The solution is Lego. This pic pretty much explains the whole process:


TIP: Sand additive

In addition to the usual additive powders like iron or bronze (expensive), I tried beach sand. The result is interesting, and differs greatly with the type of resin used (clear or white). The sand sinks to the bottom, so don’t expect a uniform distribution.

Warning: Shelf life

Smooth-on will gloss this over, but the truth is that these products have a very short shelf life. Resin will start going bad after about 6 months, even if it’s in a sealed container. Don’t buy big volumes unless you intend on using it. Bad resin will foam when curing, and will overflow from the mold and is generally nasty.