Casting Setup

There are a large variety of castable materials with various consistencies, colors and other material properties. The information in this post only covers a selection of such materials that I’ve experimented with myself.


Smooth-on is a great resource for all things castable! >>


Brilliant Resin
This resin is great for casting transparent coating over electronics!
Little Windows >>

Easycast clear casting epoxy
(have not tried it yet)

Smoothcast 326
A clear hard resin that can be mixed with pigments to give it colour. The best results I’ve had with this material is with casting sheep lights.


Smooth-on Ecoflex
Ecoflex is a really nice soft, squishy silicone that is easy to mix. But i’ve been having problems creating a mold.
Smooth-on replied: “There is a chemical interaction between OOMOO and Ecoflex which prevents Ecoflex from fully curing. You cannot pour a platinum silicone like Ecoflex into a tin silicone like OOMOO. One option would be to pour Ecoflex into another platinum silicone (Mold Star could be used, for example: ). Release agent (Ease Release 200 or equivalent) is required to separate the silicone from silicone. Another option would be to create a hard mold out of a urethane plastic such as Smooth-Cast 300 (simple example: ) or Shell Shock (simple example: ). No release agent is required when pouring silicone into one of these molds.”


While not good for casting voluminous shapes, latex is good for applying to surfaces.

Mold Making

Mold Star
(have not tried yet)

Smooth-cast 326
Casting urethane foam prototype in Smooth-cast 326 didn’t go so well. I think the heat from the curing process not only deforemd the palstic container, but also forced air bubbles out of the foam making it inflate the Smooth-cast just as it was turning hard. Ops.

Moldgel Silfree
While nice to work with, this algy-based mold material is doesn’t produce great results if you’re looking to cast multiples. Also, the Smooth-cast 326 that i cast into this mold cured very slowly and with lots of bubbles. Not sure why.

Is a great tin silicone for casting soft, durable molds – only not to be used with platinum silicones like Ecoflex (see above)!

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