Well, my problem is that I would like to build a lightweight structure for a telescope. One possible structure is truss serrurier structure, like this http://www.planewave.com/index.php?page=1&id0=0&id=4 . Another ideea is something even lighter, like this one http://www.alpineastro.com/LAZZAROTTI/Lazzarotti_Home.htm

I don't have any experience with different materials like Al, or carbon fiber, but I've startet to study this problem. The first ideea is to make a truss serrurier structure:
- three rings cutted from carbon fiber plates: one full disk (plate) at the end to hold the main mirror and two rings in the middle and at the top of the structure
- truss tubes in between
Tubes will be something like this ones https://www.easycomposites.co.uk/8mm-woven-finish-carbon-fibre-tube , pulllwinded or rolled.
The main problem is the ring elements and the back plate: must be light and strong. And I've concluded that single carbon fiber plate is not good. It must be a sandwich plate. I found this https://www.easycomposites.co.uk/foam-cored-carbon-fibre-panel but I don't understand: is fiber carbon on both sides?

The tube must hold a 11" (270mm) mirror at the back (~4kg) plus the focuser (~500g) and a small mirror at the top (~400g), Truss must be ~1m long and 350mm wide.

I plan to glue the tubes on the rings/plates in order to avoid drilling holes and weakening the structure or cracking the tubes.

I'll appreciate any help.
Thanks.