Silicon Moulding of 3D Prints – Part 2

After quite a hiatus, we’re up raring to try out our silicon mould and casting techniques again on 3d prints! This time though, we will try to make things a little easier by slight tweaking the initial mould box and getting that also 3d printed out, instead of forming it out of acrylic like we did before in this earlier post.

The model up for experimentation this time is a great scan of an Head of an Ogre by tomburtonwood. You can grab it from the link too!

So this is what it looks like when the STL model file is opened. For this case, its important that the model comes with a flat back surface.


From there, it was a simple matter of modelling a mould box around it. In order to save on the silicon mould material, we opted to make quite a tight box but allowed the side walls to go about 3 times the height of the model. This comes in really handy as we’ll see later on.

02 - Ogre Model in Mould Box

All modelled up and then we spun it through the handy Makerbot slicer to get it ready for print. Ain’t going to go deep into that as that’s the easy bit. Here’s the physical 3d print on the right. The model on that left is already a reversed negative model box which was also found on thingiverse but in the end didn’t turn out well (so we’ll ignore that…)

03-Printed Mould Box and Another

As per the steps, pour the A-B 50-50 volume mix of silicon into the mould box, carefully and slowly to avoid trapping air bubbles in it. As you can see. hand protection is handy (heh, see what we did there?) here more to so avoid messy goop getting on you.

05 - Always with Protection

Then it’s time for some patience as the silicon mould sets. Best to leave for a full day for it to fully cure before demoulding.

04 - Silicon Mould Setting

Next day, simply pop it out and tada, a perfect negative silicon rubber mould of the original object!

06 - Demoudling

And here’s the really nifty part – because the silicon rubber mould was cured in the box enclosure, you can simply flip it around and fit it back in to get a rigid structure to hold your mould for the resin pour.

07 - Fits Right Back in

Stage 2 just sees us mixing up the 50-50 vol resin material for pouring and…

08 - Pouring the Cast

A quick and careful pour gets the material into the moulds. This is almost an after-picture as white generall means it’s near the end of curing. They start of as a kind of translucent pale colour and you see the white bits slowly bloom as parts of the material cure.

09 - Waiting to Set

Pop the rubber mould out, then pop the recast piece out and voila – great replica of the original piece in much less time than it would take to have printed a new piece! Also, the fidelity of the recast is so good that the 3d print layer lines can still be seen.

10 - Finished Result

Well, that’s it for now – a simple trick to make recasting piece much easier. Maybe more complex 3d prints and moulds will come soon in the future! 😉





Comments 4

  1. Nice and simple tutorial,would like to try it out some day but where do you buy the Smooth On resin and silicon?

  2. Hi, just looking to make some chocolate moulds. Did you use a release agent before pouring in the silicone?

    1. Hi David,

      For chocolate moulds, you should ensure that the silicon used is food grade ones. We didn’t use a release agent before pouring in, and should be the same for your case if your silicon is of high quality. But it doesn’t hurt to spray release agent either, just make sure that’s food grade too. All the best! =)

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