Hi Stephen, did you get your steel? I'm at the design stage I went to Malouf Steel in Brooklyn today and purchased a 300 x 300 x 10mm base plate and 168 dia x 950mm rolled tube for just under $60!
Chris that is one solid pier! 20mm thick flanges! Makes mine sound a little inadequate
I came across a laser cutter who will cut the top flange in a circle and also cut the angled 200x50mm gussets.
russ