I was just directed to an item on AliExpress which I found somewhat interesting:
https://www.aliexpress.com/item/1005005833597374.html
I'd love to convert my GSO 8" F5 Newt to a much lighter carbon fibre tube.
They seem to be listing 6" tubes for Skywatcher so I'll possibly contact the seller later (or not, I couldn't really afford it if I wanted it at the moment) but one day.....
As is there's no reviews and no comments on this companies products (or this one anyway) I wouldn't be jumping the gun but it still seems interesting.
I notice every day the 8" GSO gets just that tiny bit heavier.