This is amazingly easy to do, once you have the necessary materials.
How to make a Necron Crystal Forest
The first crystal is made by a company called APM Corporation. They specialize in making plastic ice items, so if you are doing an ice planet then they will probably have everything you need. They can be found here
. I have used a shiny surface as the base because it greatly increases the light effects. The smaller crystals I picked up at the craft store. They come