Basically, it's a bucket with perlite and vermiculite in it. I'm not sure exactly how they are made, but I know it's mainly just perlite. They have been VERY good grow systems for growers. I myself have seen quite a few successful grow journals involving hempy buckets.
There is a very helpful member of this fine site named, BONEMAN. He's a hempy bucket guru.
you don't need the vermiculite it just settles to the bottom and forms a brown sludge. just 100% perlite works great. how big do you plan on letting your plants get?(this will tell me how big a bucket you need)