Rookie question so bear with me, please.

So I am using surface modeling to create complex geometry that will be used to create a pre preg carbon fiber mold. Since surface models don't have any thickness how is it possible to define the material properties to do simulation work?

and secondly,  when you have a part it is going to have a defined thickness in certain spots, it is not possible to create a shape with no thickness in real life. so how would i give my models thicknes ?