How do I get a product assembled? (Not manufactured)

I am trying to create a product, but the materials I source are from many sources, it will all have to eventually trickle down into one factory where the product will be assembled.

Does anybody here know any assembly companies that will assemble products with the materials your provide them?

I am still a beginner to this stuff, so any information will be appreciated.

Thanks

from How do I get a product assembled? (Not manufactured)