How To: Make a Mold

So, I decided to share some info on making molds for casting figures...or anything else you want to replicate. It is a great way to replicate figures that you want more of. I prefer to do a 2 part mold for replicating figures. To do this you will need a few materials; here is what I use:

1. Silicone: I prefer Oomoo 25 by Smooth-cast
2. An adjustable box: I prefer to use Lego's
3. Clay: I just buy the cheapest stuff at Wal-mart that will not dry out...not oven bake. 
4. Plastic Cups: These need to be clear, disposable is the best option.
5. Permanent marker
6. Stir stick: Longer then your cups is nice.
7. Measuring material: I use rice, just don't plan on eating it afterwards.
8. Mold Release: I use Mann Ease Release 200
9. Tooth picks

I will explain how what each is used for in the following steps. Note: it is important to do these in order to achieve good results.

Step 1
Build your box out of Lego's to the desired size. The box should be built as to conserve material but, not to small as to hinder the placement of the figures.

Step 2
Begin filling the box with clay and then place the figures into the clay. I usually put about a half inch down before placing the figures. Because I like to cast my figures with bases it requires bigger boxes, more clay, and more silicone. You can remove your figures from their bases to cut down on materials. Notice I will need to add more Lego's to make sure my bases get completely covered once I pour the silicone.

Step 3
Now that the figures are placed you can see that there is space between them and the clay; this is because I like to include the bases. Fill in the spaces with clay so that the figures on supported by clay. Be careful not to push the figures up with the clay as this will cause problems with the second part of the mold. The figures should just be laying within the clay.

Step 4
Time to measure how much silicone we will need for our mold. I use rice because it is cheap and easy to remove from the clay. Simply pour the rise into the box and fill to the top.

Step 5
Remove the rice, placing it into a clear plastic cup. Mark the top of the rice with the permanent marker.

Step 6
Pour half of the rice into a second plastic cup. Confirm that you have half of the rice in each cup, then mark the top of the rice on the first cup. One of your cups should now have 2 marks on it. You can keep the rice to reuse or throw it away now.

Step 7
Cut and place tooth picks connecting the figures. Doing this creates sprues that allow the plastic to flow through all parts of the figures and in between the other figures/parts in the mold.

Step 8
Make "locks" by pushing an end of a pen or something. Doing this will help the two pieces of the mold line up and stay together once completed. See picture above.

Step 9
Spray with the mold release and let sit for a few minutes. This help prevent the silicone from sticking to the figures, clay, and Lego's. Really the silicone shouldn't stick to these items but it doesn't hurt to do it now as it will be extremely important later when making the second piece of the mold.

Step 10
Time to mix up the silicone; it is a two part mixture which is why we measured with the rice and marked our plastic cup. Take one of the silicone bottles and fill the cup to the first line. I prefer to pour the thicker of the two parts first, which is the yellow bottle if you use Oomoo 25. 

 

Step 11

Pour the second part of the silicone into the cup, filling to the second line and mix. 

Step 12
Pour into the mold. To help reduce the formation of bubbles and to remove the bubbles created from stirring I pour from about 3 feet above the box. Also, pour into a single part of the mold until the figures and clay are completely covered. Now leave it for a few hours while it sets up.

Step 13
Once the silicone is completely set up you can remove the clay. You can take apart the Lego box completely or just flip it over and remove the clay. Make sure to remove all of the little pieces of clay that may stick to the figures.

Step 14
Reassemble the Lego box with the first piece of your mold in place.

Step 15
Spray with the mold release. This is very important!! If you fail to spray it the next portion of silicone poured will fuse to your first piece.

Step 16
Mix the silicone. See Steps 10 and 11.

Step 17
Pour the silicone into the box. Refer to Step 12.

Step 18
Take the Lego box apart and separate the two pieces of the mold.

Step 19

Remove the figures and the tooth picks. Now you are ready to start casting figures.