2-Part 3D Object Mould of an Anatomical Heart

To challenge myself, I decided to create a 3D object mould. Since I had never made one before the first step was research these types of moulds to understand their concept and functionality. I chose to sculpt an anatomical heart because of my strong interest in anatomy and physiology. After planning out my sculpture and mould it was time to get started.

I used a 3D Anatomy Atlas app to guide me in sculpting the heart. The app was incredibly helpful, allowing me to rotate the heart and view it from any angle. For this project, I used grey plastiline clay, not for any specific reason but simply because it's my preferred material. I thoroughly enjoyed the sculpting process, as it was my first time creating something like this, and it definitely challenged me. While there are many aspects I'd like to improve, those will be projects for another time.

Once the sculpt was complete, it was time to start making the first part of the mould.

The first step was to decide where the seam of the mould will be. Once I determined this, I covered the bottom half of the sculpt that will be moulded later, with a wet paper towel to protect it from the WED clay. I then placed it on a bed of WED clay, covering it up to the seam line trying to make it as level and smooth as possible. Once it was all smoothed out, I carved out circular keys into the clay. To ensure the sides of the mould were even and smooth, I walled it up with foam core boards, as I find this method more effective than using WED clay.

With the walls in place, I added a pour tube to my sculpture and sprayed the entire setup with a release agent before pouring in the plaster. I decided to integrate the pour hole into my sculpture by incorporating it into one of the arteries. However, I mistakenly carved out my pry holes at this stage, forgetting that all negative carvings in the clay would become positive in the mould. Fortunately, this mistake was easy to fix later.

One de-moulded i left the heart sculpt inside of the mould to not ruin the seam and just cleaned up any staining and left over WED clay from the plaster. This was also the step where i chiseled off my failed pry marks and instead replaced them with some plastiline so after this part is moulded, that will be negative space to help pry the mould open. Then I walled it back up with foam core boards and sprayed it down with a releaser which is important as plaster will be poured over this next, as plaster sticks to plaster its necessary to created a barrier between the two to not give them a chance to bond or else you wont be able to open the mould. After this the plaster was poured in.

This was the finished mould, ready to be casted.

The casting process for this mould was quite a journey. Initially, I tried to pour the silicone into the mould, but the small size of the pour hole made it impossible to beat the quick setting time of the Platsil Gel 25. As a result, I repeatedly ended up with only half of the heart. However, I was determined to make it work.

On my third attempt (yes, I had already failed twice), I decided to try a different approach. I filled the first half of the mould as usual, but then, once it was closed, I used a syringe to inject the silicone. This method seemed promising and took half the amount of time compared to my previous attempts. However, when I removed the cast, I discovered that the heart was still not fully cast—about a quarter of it was missing!

As demonstrated in the video, I decided to stand the mould up on its side to use gravity to my advantage while filling it with silicone, ensuring the highest part of the sculpt was properly filled. I used a syringe once again to inject the silicone into the mould and secured it tightly with a strap to ensure it remained shut.

Once set and de-moulded, this was the finished product! 4th times the charm!

To conclude, creating a 3D object mould involves many considerations. One of the most crucial aspects is determining the seam line, as well as deciding where to place the pour hole if there is no flat part of the object. This process can be lengthy and requires multiple trials, but I am pleased with the final result and everything I learned along the way.

Thank you for reading!