Morning all

I have been thinking about making my own roof rack and was wondering if anyone had any ideas or suggestions for me.
My thought has been that to make it from say 20x3mm flat bar would mean that is lightish but strong and durable and I will then be able to add to it if needed.
Aluminium would be lighter but I have no skill in welding it, perhaps the "connect-it" pieces from Maizeys plastic would work?
The problem there being that the corner pieces would wear due to the elements.

Any ideas? All will be appreciated