Casting resin in silicone putty molds

Creating resin Legos with reusable silicone molds

After my post last week about creating silicone putty molds to make Lego crayons, a few of you remarked that doing that was all well and good, but you wanted to see how well resin did in the molds.

Okay.  Let’s do it.

Transparent yellow Lego resin minifigure

I mixed a batch of Resin Obsession super clear resin and grabbed the first colorant I happened to find.  It was the Alumilite yellow pigment.  (Yeah, I can get a little crazy like that sometimes.)

Mixing yellow pigment into epoxy resin

I filled each mold cavity with resin and allowed it to cure overnight.

pouring resin into silicone putty Lego molds

Demolding went as expected.

demolding resin Lego minifigure from silicone putty mold

Here’s are the results:

The Lego brick cast with a nice shiny finish.  The only blemish was a mistake I had made.  When I pushed the putty around the brick, I left a small gap which created a line up next to the brick.  That line filled with resin. (The same thing happened with the wax Lego brick, but it was much more noticeable here.)  It can be sanded off (GRR!), but it’s more of a technique note for me to be aware of next time I use mold putty.

Lego brick casting from silicone putty mold

The Lego minifigure also turned out well, although I have a few technique points to remember there as well:

1.  If I want the head to be more round, and not have the overflow that needs sanding, I need to push the mold putty more around the head.  Otherwise, I need to sand him with a flat back.

2.  When I first looked at the minifigure, I noticed his chest had a rougher finish than the rest of his body.  (The rest of his body was a very smooth matte finish.)  I immediately checked the crayon version and saw the same roughness.  It must be from the sticker on the Lego.  A light coating of the Resin gloss sealer spray should help to shine him right up.

3.  The hands cast much better.  (They broke off last week in the wax version.)  There’s a little clean up to do, but I was happily surprised with the results.

My overall impression on using mold putty to cast resin items is that it works well for flat backed pieces, but something with some dimension may not cast as ‘smooth’ by the looks of all the clean up I have to do.

Lego minifigure resin and wax castings

What has been your experience with using silicone mold putty to make molds?  Is this something you want to try?


Unpublished Blog Posts of Resin Obsession, LLC © 2015 Resin Obsession, LLC

Like this post? You may be interested in  Painting on resin - Can you paint on resin?



I used the Amazing putty to make a mold of a dragon pendant I really love. Yet, each time I cast resin and let cure, it always comes out soft and bendable. Is it the mold or the resin? I’ve done this several times, trying to be mindful of preparing the resin, but am still getting the same results.


I used Envirotex Jewelry Resin the first couple times, and I now just tried it with Ice Resin (syringe form). Maybe the mold isn’t deep enough or to small and intricate to harden?

Katherine Swift

Envirotex jewelry resin is meant for bezels, not molds. How deep are your castings? I’m guessing not much if you are only using Ice Resin from a syringe?

Katherine Swift

I’m wondering if the castings are too thin. Even if they are fully cured, they can still be flexible.


Yep – they are thin. The deepest part of the mold always hardens without fail while everywhere else stays soft. I actually tried making a much deeper mold, and it took a couple of days before I noticed it – but that casting did finally cure hard.

Would it still be okay to paint the resin on the original pendant to preserve?


Hi just wondering which putty gives a glossy shine I want to cast water clear resin prices and everything I try in my moulds is dull so I wanted to make my own moulds but can’t find a putty that has a gloss finish when set.
I’m in the uk can anyone advise on a type of putty or mixture that will achieve this

Katherine Swift

Hi Rebecca, if you don’t use shiny templates to make the molds, then castings from the mold won’t be shiny regardless of the molding material. This video on the Resin Obsession youtube channel explains more:


Leave a Reply

Your email address will not be published. Required fields are marked *