Based on your context, this makes the most sense to me. I could also be an actual "device" or "tool" used for shipping, but I cannot tell this from the context. Good luck!

would encompass both ideas, is neutral, and there are many hits on google

If you page up "Transportmittel" in google, you'll find there is a wide range of definitions from simple packaging to pallets and other aids to moving. It might be better to use this "grapeshot" approach, unless you know exactly what is meant.

just a guess

This is the answer.

The Akademie Herkert defines Transporthilfsmittel as follows (see first reference below):

Da es nur in wenigen Fällen sinnvoll ist, Güter lose zu transportieren, werden Transporthilfsmittel eingesetzt, die mehrere Güter zu Ladeeinheiten zusammenfassen. Transporthilfsmittel umfassen z. B. Behälter, Säcke, Paletten und Container.

(operative phrase: "mehrere Güter zu Ladeeinheiten zusammenfassen")

Here's the Wikipedia definition of "unit load formation equipment" (see second reference):

Unit load formation equipment is used to restrict materials so that they maintain their integrity when handled a single load during transport and for storage. If materials are self-restraining (e.g., a single part or interlocking parts), then they can be formed into a unit load with no equipment. Examples of unit load formation equipment include pallets, skids, slipsheets, tote pans, bins/baskets, cartons, bags, and crates. A pallet is a platform made of wood (the most common), paper, plastic, rubber, or metal with enough clearance beneath its top surface (or face) to enable the insertion of forks for subsequent lifting purposes.

This Wikipedia definition was taken from this website on materials-handling equipment:

http://www4.ncsu.edu/~kay/mhetax/UnitEq/