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.


Written by



Shachar "Vice" Weis is the founder and CEO of Packet39, a developer of Virtual & Augmented Reality custom software and hardware solutions for the manufacturing, power and aerospace industries.