My tree is based on Fasteddy's. Mine has a flagpole at the centre with the twelve uprights made from 25mm conduit. The cross pieces are bits of flat aluminium screwed onto the flagpole and then the conduit is attached with cable ties. Now I got away with a basic flagpole at the centre because mine is attached to my house at the top and therefore relatively protected from the wind. If it is going to be free standing then other have suggested a stronger single piece of metal pole as your standard flagpole isn't that strong. I have the base sitting into a sun umbrella base which is marble and quite solid.