💗 Week 10 – Molding and Casting

Week 10 – Molding and Casting

November 2025

This week was mainly about molding and casting.

What I Did

Follow this link to the group assignment.
Design and crafted a pony figurine using molding and casting techniques.
Explored different materials for molding and casting, including silicone, drystone and chocolate.

Mold Design for Pinkie Pie

First I designed a 3D model of Pinkie Pie(the pony from My Little Pony) using a free online image2model converter and refined that with Blender. Check out the image I used and the final 3D model I have:

Then I imported the stl file to Fusion 360, ensuring that the model had appropriate undercuts and draft angles for molding. The model was then 3D printed using PLA material. 3D Printed Model

Editing 3D Model in Blender Sculpting Mode 3D Printed Model

Model for Molding in Fusion 360

Molding

The PLA model serves as a master mold for the silicone rubber casting, which is then used as the final mold.

In the video on the left, I melt a layer of beeswax that I painted on the PLA mold and it leaves a thin layer in the valleys which can improve surface finish. It was relatively fast to apply and easy to remove.
Then mixing the silicone rubber A and B components in the correct ratio ~1:1. The mixture was poured into the mold and put under thermal lamp to cure.(Takes ~1 hour)
After curing, I carefully demolded the silicone mold from the PLA master model. The result is shown on the right. The part coming between the legs was particularly challenging to mold.

Casting

The silicone mold is used to cast the final piece in a material of choice, such as drystone, resin, or chocolate. And lots of fun came along!!!

Drystone Casting

I first opened the area under the feet and used a syringe to inject the drystone material into the mold.
Two acrylic boards were used to clamp the mold tightly to avoid leakage.
After letting the drystone set and harden ~ 50 mins, I carefully demolded the drystone pony from the silicone mold. The final result is shown on the right. However, the pony tail didn't come out. So later I tried to open another casting path from the end of pony tail.
I also tried with casting the front and back separately and then joining them together.
Overall, the drystone casting worked well, producing a solid figurine with good detail.

Chocolate Casting

I used a type of edible rose gold glitter before casting the chocolate.
After the chocolate was poured into the mold, I let it set in the fridge for about 60 minutes.
The final result is shown on the right, which is very pretty and would be ideal if the process is food safe.

Final Touches

I intentionally left the toolpath visible on the hair of the pony and sanded the body a little bit.
I applied a layer of UV resin to fix some cracks happened during demolding for the drystone cast.
The UV resin was cured using a UV lamp, which hardened it quickly and created a smooth surface.

For drystone casting, I added a layer of acrylic paint to enhance the color and details of the cast.

Here are the final results of my pony figurines casted in different materials:

Then I realize that the pony is clearly staring at something, so I 3D printed a cake and a holder to go along with it:

Other Notes

It's my first time to use sculpting mode in blender and it turns out amazingly useful. Important note also is to have a good use of the mask for quick selections and editing, which greatly speeds up the workflow.
I was also investigating the use of epoxy for the snakes of the hourglass in my final project and it will be updated on the final project tracker page.