Step 1: The Silicone Mold
Elastosil M4503 by Wacker Silicones combined with Wacker Haerter T-35. Random clay for the first layer of silicone poured, use Klean Klay or something similar instead.
The first thing I did was to get a big bag of my LEGO collection as a kid. I estimated the measure I would need to fit my model without using too much silicone but still remaining within a safe limit to avoid a flimsy mold. I then proceeded to build a giant castle of LEGO! To my surprise, this was not as much fun as it was when I was a kid 😉
After the Lego was built, I filled half of it with clay and inserted the toy inside. As you can see, I put the body into the clay top-down. This was actually a really bad idea! It could make it nearly impossible to extract the casts as the body is stuck inside the silicone. What I should have done is to have flipped it around 90 degrees to the side.
After this, I added small holes with a pencil in the clay all around the model, so that the silicone would fill inside and create a locking mechanism to combine the two pieces later. Someone on Flickr pointed out that I had made these too deep, but they served me well through the process as they are. I then created two vents using some pencils at the ears and a pouring tract at the top. That is where you will be later be pouring the resin into. This tract should be much larger than the pencil-sized ones I made. It should also be formed as an up-side down cone for ideal pouring. I had to cut this with a scalpel at a later point as once again some of the excellent people from the “Resin is the new Vinyl” Flickr group pointed out.
The left ventilation tract was a very bad idea, I filled this up with silicone as it makes no sense. The resin would just pour out to the side!
I then built up the LEGO so it would cover the entire husky. I mixed together the two-component silicone (Elastosil M4503 & T-35) and poured it down onto the husky from as high up as possible to avoid air bubbles. Remarkably, this technique and/or choice of silicone had no air bubbles at all. The silicone then needed 20 hours to cure.
After that was done, I turned it upside down, removed the clay and then poured another batch of silicone on the other side, filling up the LEGO castle.
After another 20 hours, my two pieces of silicone were done! This silicone didn’t even need the silicone mold release spray that the Smooth-On YouTube videos say you should use. It came out quite easily, but I’m sure it might be even easier if you did use some of that spray. I think it depends on the silicone and what your model is made of.
All ready for casting…
My Flickr Set
Resin is the New Vinyl Flickr Group
Rapid Prototyped Chocolate Monkey Faces
Yoshii’s ZBrush Toys
Smooth-On Mold-Making Tutorial Video:
Freeman Supplies Tutorial Videos: