Custom Lego Clone Helmets and other pieces

I am trying to figure out how I can make custom helmets, weapons, etc...
If you guys know of any way to do it, please let me know. Preferably using silicone molds.

This topic is only about information about how to get stuff I need to make it. DON'T post things saying how you want it also, or other things like that.

if you want to make good helmets use Resin Casts they're very good for the job