I sell liquids. The handling and transfers of my product too often ruin the product and the customer, rightfully, returns it. I see how Amazon ships me the returns and hear from friends about the condition the product arrived in. I want to ship these items to amazon, packed in my own mailing box. All Amazon would have to do is put a label on it and ship to the buyer. All liquids I sell need to be in a bag with a suffocation warning on it. Can I put the bottle with the liquid inside the bag; put bag and bottle inside the box; and put the FNSKU label on an end panel of the mailing box? Would FBA object?
No, that’s the right thing to do. Amazon even offers a “shipping ready packaging” program (but it isn’t accepting new enrollments at this time) that encourages sellers to prepack their goods in a way that they can be safely shipped without requiring additional packaging. It helps ensure customers receive their goods intact and helps Amazon save on packing materials and reduce shipping times.
If you box your product as you’ve described keep in mind that both your dimensions and shipping weight will change. Amazon adds 4oz to the weight of your product when determining the FBA fee, so if your new packaging adds a few ounces and Amazon adds another 4oz you quite likely will see your fulfillment costs increase to the next weight tier.