Originally Posted by Naiagu
If you make a cast out of cardboard you could use expanding foam as well. You can buy it at any Home Depot, it comes in a spray can and expands overnight and hardens, it's quite light too. It'll look like a blob at first but just grab a cutting knife and you can carve the shape you want. The foam is about $4 a bottle.
Yoooo~ thanks a bunch!, I also forgot about this alternative, I remember reading about it a while ago, but I got busy with other stuff and forgot all about it. I'll have to hit up this option also.