These are always a favorite and so easy to make. See my recipe for Chocolate Covered Oreo Cookies for complete directions and pictures. The molds are made out of plastic and you can make 4 to 6 chocolate covered Oreo cookies at a time.
There are quite a few available online from my favorite new source, spinningleaf.com. The best part is their molds are cheaper! They have more molds than I have seen anywhere and even the mini molds for bite size Oreos. See Kitchen Gadgets – Mini Oreo Cookies. Remember, spinningleaf.com has a lot more molds to choose from, just visit their site. Also, I have not taken pictures of every mold I have… Recently (9-22-13) I posted a number of Halloween Oreo Cookies and (12-23-13) posted Christmas Oreo Cookies; Valentine Oreos for your Sweetie.