The centre holes were cut next and the rear plate 'fettled to fit, there was
a need to cut a slot on the top for the cylinder base to fit through. Oops!
Rear plate sorted the corner posts were attached and secured,
I used 4 long roofing bolts for this, I'm going to fit some alloy tube
over these latter.
The top plate was adjusted by using the corner nuts to get an even fit.
Once happy with the spacing the corners were secued using nuts.