I need to set up my attributes so that people can select more than one of the same attribute.

Scenario:

Product: Jacket

Product Attributes - things I can customize my jacket with

Silver dots (.50 each)
Gold dots (.50 each)
etc.

But, I need to be able to allow people to say:

I want 10 silver dots, 15 gold dots etc.

How can I do this?

Thanks!

OregonBum