I feel like the designer should be in charge of making the product. You website should simply serve as a way for them to get the design out there. Again, I thin

I feel like the designer should be in charge of making the product. You website should simply serve as a way for them to get the design out there. Again, I think taking notes from Kickstarter would be good here. Let the designer decide how many pledges they want before they will produce. Once this number of pledges has been reached, you take a cut. Then all of the shipping information for the pledgers is passed from you to the designer and they are in charge of filling the orders.