Fasteners for thin (ish) GRP panels

[Iowstratos]

I have not got the rivets to hand, but hears an anchor nut, floating type.
They were good of the worlds largest hovercraft, heaviest flying boat, fastest accelerating interceptor plane, woulds fastest cars, and the only satellite rockets.
All made on the Isle of Wight!

[Fingers]

I know the ones, they work well. I bought some metric ones the same to use in my Stratos.