When using a partner lab to fulfill print orders, shipping profiles specific to the lab are available and must be used.
Partner labs can either ship products directly to your customer ("drop-ship"), or to you.
To enable/disable a shipping method, simply check/uncheck the corresponding box under the pricing profile's Tax & Shipping.
When the lab ships directly to your customers, the shipping options and prices are directly linked to what the lab will actually charge you. You can optionally also define a markup on the estimated costs.
Shipping directly to your customers is by far the simplest option.
When the lab ships to you, you can create a fully customized shipping profile to define your own prices. Note that you must then aim to recover both the shipping costs charged by the lab when sending products to you, and the costs of forwarding to your customers.
This option is useful when you must review the products before forwarding to your customers, or when your customers can physically pick-up the products from you.
This option can also be handy to ship to destinations not covered by the lab, or when the lab's drop-ship prices are prohibitive.