Cute food, as usual!

May I ask where you got the siliconey stuff? I keep looking around on the internet but i dont know what its called exactly, so I dont know what is the right stuff.
meltedcrayons and
Amikoko, there are various brands of
2-part silicone molding putties available. Each will have a somewhat different set of characteristics for its curing time, color, smoothness after curing, and heat-resistance after curing, etc.
They are all good for polymer clay** but the best characteristics for clay I've seen yet are from the brands called
Alley Goop and
Miracle Mold (those have to be mail ordered though since only Amazing Mold Putty is available in craft stores as far as I know... haven't checked art supply stores however).
**molds made from silicone can capture really good detail, they allow for undercuts and even some "completely-surrounding" molds, and they can even be put into the oven with polymer clay or with liquid polymer clay in them since even the lowest-heat-resistance brands will take our curing temps
If you're interested in lots of info, lessons, examples, etc. of the different brands of 2-part silicone molding putties, check out this page at my site:
http://www.glassattic.com/polymer/molds.htm...click on
2-Part Silicone Putties, but mostly read the sub-category under that called
Brands That page also has a lot of other stuff about using all kinds of
molds with polymer clay, and even
making molds with polymer clay. For those click on some of the
other categories on the page.
In the case of molds for creating Oreos, you could always make an Oreo-type surface yourself from clay, then bake it and use it for a making a mold for the final Oreo surfaces, or you could just use a real mini-Oreo cookie to make the mold. You wouldn't really need to use a silicone mold though... polymer clay can make quite good molds too if they're done right.
Diane B.