Sturdy shed. 4"x2" frame studs on 16" centres, with 4" corner posts set 18" into the ground with concrete. Entire structure ply lined with exterior 9mm ply, roof shigled with mineral felt ontop of 18mm OSB (pavillion type roof) 10mm^2 power supply from house with it's own small consumer unit.
Shed took 3 days to build (whilst avoiding the rain!) the combination of lots of 2x4s plus 4" corner posts and being set in the ground means there is very little movement in the structure.