Making the mold box with acrylic or Legos,make sure the materials you use will not react with the silicone.Make sure the box is water tight or the silicone will leak out of the box and ruin your mold.If you’re making you box out of acrylic seal the edges with hot glue.Make sure you can easily break apart your box once the mold has cured and reuse the parts.
Now that your box is ready for molding.Put the mold into the box and fasten it with plastilina clay,try to make the clay surface as water tight and smooth as possible.Spray the inside of the box with a mold release agent.This will aid in releasing the part from the silicone.
Now we are ready to start wording with silicone.
Open and mix part A and mix thoroughly.
Open and mix part B with a new stirring rod.
Pour and equal volume of part B into a new container.
Pour both A and B into a separate container and stir completely.
Mix part A and part B in a separate container.
Pour mixture in slowly starting at lowest point.
If you didn’t mix enough,you can add more on top.
Let mold set until cured.
Follow the same procedure as pouring side one for pouring side two.
Once this silicone has completely cured,release it from the mold box and open the two halves of silicone.
Close the two halves of the mold, making sure the registration keys are aligned.
Shake parts A and B.
Measure out equal parts by volume of A and B into separate containers.
Pour parts A and B into a separate mixing container and stir them until completely combined.
Now SLOWLY pour the mixture into the mold spout. If you pour too quickly you will trap air bubbles in the crevices of your mold. It may help to rock the mold from side to side to allow potential air bubbles to escape.
Let your cast set to cure. The plastic will heat up as it cures due to a chemical reaction. Wait until the mold and excess plastic are cool to the touch before releasing or you may damage the cast when it is in a fragile curing state.
Once the cast is fully cured open the mold and release your cast.
Once your cast is free from the mold you may want to clean it up.
Sometimes excess plastic leaks out along the part line creating flash.
This is usually thin enough to be broken off and sanded down.
Feel free to paint or modify your part!