We (Nissan) do this quite often with finishers that we send to the production lines in Spain... finished parts can be nested within each other with a layer of bubble-wrap in between. As long as there is ample padding inside the box, the parcel should pass the "shake test" and there should be zero part mutilation. I'd estimate the diffusers to weigh ~1 pound per pair... so, a bulk shipment of 20 pair shipped via DHL might be a consideration. Entire container, including packaging, shouldn't exceed 50 pounds.