DIY Silicone Molds at Home for Clay Crafts

I know there are a bajillion instructables on how to mak e silicone molds at home, but since I was working on some molds of my own I decided to make an Instructable about it. Hopefully it helps someone.
I read many, many, MANY tutorials on how to make silicone molds, with store bought silicone mold putty and with hardware silicone caulk. I have tried both. I personally find that the silicone caulk method works just as well and is cheaper.

1. Cornstarch
2. 100% Silicone caulk. Can be found in most hardware stores.
3. Caulk gun (not pictured)
4. Baby oil or mineral oil
5. Acrylic paint (optional, but colored molds help you to see the details better and help you when using the mold).
6. PLASTIC bowl and spoon. It is just much easier to clean if you use plastic.
7. Paper towels (not pictured)
8. A large workspace that you can clean up easily.

I am not going to put specific measurements because I dont use any. The amounts will depend on how much mold compound you want in the end.
Add a blip (technical term) of sliicone to the plastic bowl. Remember, you will basically end up with twice the amount of silicone you pour out, so be cautious. You dont want to waste it when you find out you made too much.
Next, add a cautious amount of corn starch. I say that because you don't want to have too much. Most likely you will end up having to add more, but start small.
Add a tiny squirt of baby oil. Not much at all. I think this helps with the flexibility, but I am going to compare ones I have made without the baby oil to those made with.
Next, add a little bit of craft acrylic paint. This is just for coloring, so you can totally skip it, but I find that it does help me to be able to see the mold better when I am using it. If you are using clear silicone, definitely use paint because you can't see a dang thing if your mold is made of that stuff (I know!).

With the plastic spoon, mix the ingredients thoroughly. Most likely, it will be too sticky and messy the first go. You want it to end up being like putty or clay.
Keep adding cornstach a little bit at a time. Eventually it will get too hard to mix together with the spoon and you will need to use your hands.
*A word on this:
You can't really use gloves when doing this; I tried. It just turns into a mess. You will have to use your bare hands. If you are worried about the silicone exposure, I get it; so was I. However, while working on a truck with a friend, we were replacing a gasket, which meant we used silicone sealant to help the gasket seal. Without hesitation, he just used his fingers to smear the silicone on the gasket. Then I thought, "Ok, mechanics do this all the time - it probably isn't gonna kill me." If you are really bothered by it, though, just go buy some ready made silicone putty and continue on your craft journey.
So, eventually your silicone mix should look like the above picture of the mold putty I am holdin in my hand. It should be slightly sticky and kinda stiff. Sort of like any putty you have played with, but a bit stiffer and less gooey.

Fetch the object you want to make a mold of. I have an original clay piece that I am trying to get ready for my Etsy Spring Collection.
Tear off a bit of the silicone putty and roll it out, slightly flatten it, and see if it is big enough to cover the object. Keep in mind that it will end up having a slight seam, so decide if you want to divide the object in half or top and bottom. I prefer doing in half; it is easier to make a mold of and easier to get out of the mold once I put clay in it.
Place the flattened sphere on your work surface. I recommend putting down a layer of wax paper because the cured silicone will easily come off of it.
Press the object into the silicone, kind of rolling it instead of just pressing straght down. Go only halfway.
Allow to cure for about 24 hours.

If you just need a flat object, the previous steps are all you need. If you are making 3D objects, though, you need to make a two part mold.
After the first half is cured, take a knife and cut little triangles or squares into the edge of the cured silicone round. These will be our interlocking pieces to make sure we can line up the two mold halves like they are supposed to be.
Next, grab some vaseline or petroleum jelly. This will be the mold release. DON'T forget this! If you do you will just end up with a silicone lump instead of a silicone mold because cured silicone will stick to uncured silicone and just become one mass of silicone.
Remove the object from the mold. Now smear vaseline all over the mold (including the triangles, or "registration marks" as they are technically called. I like to put a layer, let it sit for a minute, then do another layer. You can also use a paint brush to help you spread the vaseline.
Now replace the object into the mold.

Get a lump of silicone putty that is big enough to cover the first half of the mold. With the first half of the mold laying flat, roll the new silicone putty over the first half, making sure that it gets into the cut marks.
Leave to cure for 24 hours.

Once cured, you should be able to pop the two halves away from each other. IF you used enough mold release, that is. In the photo you can see that this mold did not want to come apart cleanly, meaning I did not use enough vaseline. Luckily, it is still usable and was not completly stuck and I was able to tear it apart.

Now you can hopefully make molds of your original creations to help you with your crafting. If you make earrings or other jewelry from clay, this can be very helpful, or if you sculpt figures you can make a base figure, make a mold of it, then modify the resulting figure into different models.
I hope this was helpful to you. Go Clay Today!