It's 2.6mm G10. I initially was going to use it for booms, but I was discouraged in that it's noticeably heavier than CF, around 35%. I want to use pure CF for my mini.
So I decided to use the G10 to replace the plywood frame on my hex. But for frame plate in this particular design, it's really overkill. I could have easily used 2mm, or even 1.5mm. As a matter of fact, using the 2.6mm, I wanted to make the inner circle diameter larger to where the G10 was only around 4mm in width at the ESCs, but my wire ring harness would have shown as it's right at 6" in diameter.
I was also confined in that I had only two sticks of 750mm CF square tube, so my booms could only be ~250mm each so I was limited to how small my outer dimension could be.
Because of the way it's designed, to only use 6 fasteners . . .each clamps the end of one boom and midway of the next. . . I am restricted to 8" props or smaller. I'm pushing it a bit, in that the prop disks have about 6mm of clearance.
But using a double plate of 2.6mm, the hex is crazy stiff. WAY stiffer than the plywood. I also put a 1" piece of wood dowel inside the square tube at the end and in the middle where the tubes get clamped. I've noticed before that 10x10mm square tube will bow out a bit if it's clamped too aggressively, and clamping force is absolutely critical.
I used a bandsaw and a Proxxon (like a Dremel) with a grout cutting tool and a cutting wheel. I had to severely limit my cutting the G10 with my band saw, because G10, as well as CF, dulls the blade QUICK. I would literally equate a ratio of 200 to 1 to cutting an identical thickness of plywood to CF or G10. You can dull a 16TPI standard hardened steel blade to uselessness after cutting only about 12" of 2.6mm G10. Ask me how I know?