I got my plywood from brims ply.
Being as each sheet is only 1.5 mm thick it bends easy as and there is no need at all to wet it.Its comes in interior or marine grade,i went for the marine grade.
It did however cost me about $57.00 a sheet.
YOU could make a 4 inch tube out of it easy as!!!
A great product what more can i say
ps i will restate that the sheets are 1.5 mm thick comprising of 3 x .5mm thick plys hence a sheet of ply that is 1.5 mm thick.
Once you laminate 3 ply sheets the strenght and rigidity is unbeliavably
cheers all ..rob