Disregarding the engineering of the bee itself (which is equally amazing) the fabrication process is brilliant. 2 things come to mind when I watch this. A. I live in the future. B. There are people out there far more intelligent than I. Consider my mind blown.
I wonder if they are working on a method to power the bee for actual flight. Of course it has no control system either at this point. Off to read more. Thanks to the poster for the link.
Look up Erik Demaine, winner of a 2003 MacArthur genius award. You may have seen him on the 'in between the folds' origami documentary. I have a feeling that this process has a lot to do with his past work in origami and algorithms.
They probably accomplish stuff faster than you but I don't think it's impossible for you to develop robots like those bees. It just that it required hard work chipping away at those little microproblems.
They showed a lot of them grouped together into a sheet towards the end of the video, so I assume the hexagon was just a prototype or made specifically for demonstration. Although if you're talking about margins between them on the sheet, I'm not sure.
Looks like this configuration would allow the highest density of units to be fabricated per given surface area. Notice that the hexagon is just barely larger than the wing span where they approach each other. Can't do the math now, but it's likely more space efficient to use the hexagon, than a plain rectangle. You'll need to use one of those shapes so you can tessellate without lose. The carbon fiber structure might not have to be continuous, though I suspect that it might play a role in positioning during fabrication.