Ha I can help!!!! My degree is helpful!
Right, you're after silicone rubber! And you want to make something know as a block mold.
Now the best way to do the mold, would be to remove the hair, and block off any holes (otherwise the silicone will sink into the holes)
Then to avoid as many undercuts, you should take the had off.
Then Stick the Head and body on seperate wooden boards, neck down.
Now what you want to do is make a box up around the head and body. The best way to do this is with lego, just build up a little house of blocks around them. Once the lego brick box is like a cm above the body parts, then you super glue these to the wooden base.
It's important to make sure that there is roughly a cm gap around the edges of the item you are molding, that way you know you'll be creating a thick and strong wall of your silicone mold.
It's best to line the edges of the boxes with plastocine, to stop the silicone leaking out.
Now once this is all done, you need your silicone rubber. This is generally white, and needs a catalyst (whihc should come with it) to mix with the white rubber, this allows the rubber to set. Each silicone comes with specific instructions on how much catalyst to use, and these instructions should be followed, but remember it's always better to over catalyised, then under.
Once you have mixed up your silicone rubber, you simply pour it into the block lego molds you made, making sure that you have a few mm above the top of what you are molding.
Leave the silicon to set, this can take up to a week.
Then when set, remove the lego bricks, remove the silicone mold from the wooden base.
Next you'll have to cut the silicone rubber, to remove the original pony. You might have to cut it a few times, anf so your molds might end up being in 5 parts.
The rubber will hold it's shape. Then you simply piece your mold back together, it's good to use pins and tape to hold your mold in place. Then you can use any molding product to mold the pony.
And there you have it.
It's important to note, that molding is a trial and error process, you might find that you need to add in air bubbles, etc, beasically whatever is required to make it work.
It's hard, and very exspensive, and you'll have to sand out all the seem lines (I don't miss the sanding from my degree).
Hope this helps
