I'm using 4 mm as my subfloor as I can get it 3.0x1.5.
For specs it varies from brand to brand but the stuff I'm using exceeds usual comp sheet as it is industrial/architectural structure speced.
Got to ulrich aluminum website and they have full specs on thier great product witch would do what you want.
Most other brands are a similar beast.
I can get a limited number of these sheets for around 80 a sheet witch is dirt cheap for solid core structural strength.
Here's the Colour
I'm not looking at making anything but we would all get it cheaper at quantity.
There are about 9 sheets, at this stage I want 3.
Location geelong
Sorry for the partial hijack but more than happy to help you out jet. They will cut , v groove and fold to your requirements