First step was to start with the big Zargs case, which is the standard fare used by NZRC, and make sure it would be big enough:
Step 2 was to get some foam sheets of various thicknesses, so that I could keep everything safe in there, so that enthusiastic baggage handlers wouldn't be a problem. Clark's Rubber in Australia is the convenient retailer for that sort of thing. Of course, retail price is not ideal, and it cost about AU$400 for enough foam to fill the box completely.
From one of the 75mm thick layers, my wife and I cut the holes to fit the eight prototype Mesh Extenders that currently exist, as can be seen below, while unpacking the kit in NZ:
Thinner foam layers were above and below in the box, and had solar panels, cables and tools interleaved among them.
My feeling is that we should be able to easily fit 16 units and two solar panels and all associated cables and bits and pieces in one of these cases without great difficulty. If we forgo the solar panels, then 24 or 32 would be possible. However, that is: (a) a lot of Mesh Extenders; and (b) you still need some way to power them.
Thus my feeling is that 8 or 16 units per case, with a richer set of accessories will be the norm. This also allows each fly-away kit to be more affordable, and for Mesh Extenders to be more easily distributed, rather than having to split the contents of a single case.
With a 40W and 20W regular glass solar panel, the eight Mesh Extenders and other parts, the whole thing weights <23kg, making it easy to ship as an extra bag by commercial airline, which is an important design goal.
One thing I did discover when traveling with a huge metal box that says "Emergency Response Unit" in large friendly type, is that it didn't exactly have the same effects as the word "Don't Panic" on the Hitch-hiker's Guide to the Galaxy. Basically they viewed it as being Not Personal Effects and wanted to see appropriate paperwork on reentry to Australia, to see if they could charge me import duties.
Because the kit was only out of the country briefly, it is in principle possible to export and re-import without any customs liabilities, which I managed, however, if I am going to do it confidently repeatedly in the future, there is a pile of magic paperwork that I need to explore. Exporting to Vanuatu for the pilot similarly requires some special paperwork on the Vanuatuan side, to ensure we are able to use their customs exemption for foreign aid projects. Another whole interesting world that I am slowly becoming acquainted with...