Guys

I am in the planning phases of my project and need to find out more about what type of material to use for my gantry uprights.

I've been looking everywhere but cant find any info on types of aluminium and or the numbering that goes with it and generally what its good for. I know its a beeeg subject but i need to start somewhere, so any help will be .... well erm helpful

Can someone please give me some info on this or just point me to some theads/links pls?

Thanks