Hollow tubes first crush, then break (bend a straw until it kinks - that's what happens) so you'll want reinforcement blocks. The forces on a mast are mostly lefty-righty, so I have chosen to orient my mast with the wide sticks going lefty-righty, and the smaller sticks going fronty-backy. I taper my reinforcement blocks so they don't end in a hard edge against the smaller sticks. Most of the stuff I will attach to the mast will be near the bottom or the top - so I have made those places solid - 4' at the bottom and (probably excessive) 2ft at the top.