Help with a science project

[Aerozord]

Now if you know me you know I love space colonization. To me step one should be orbital colonies, so I wanted to make a calculator tool for estimating construction cost of an O'Neil Cylinder pair. I can find the dimensions of the colony and know it was designed with steel as the main construction material but without knowing some basic stuff like the thickness of the walls (assuming they are even solid) I can't calculate the structures mass.

So I thought I'd call on the NPF to help find some numbers

[MasterOfMagic]

I found this:
http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20070032685.pdf

Pretty interesting stuff. Combine it with the EmDrive and...

[Aerozord]

That was helpful but it doesn't seem to have numbers for construction material.