Really handy for casting anything using polyester resin or any other hard setting resins. There are various materials available such as silicone and stainless steel. For creating many forms of the same type it's recommended to use silicone moldings. For creating orgonite pyramids use stainless steel molds for best results.
From searching online for appropriate mold sizes and shapes ebay and Amazon have the best deals on offer.
Below you can find some I have especially pulled out and have used myself to great satisfaction.