[telkanuru]

I'd say for a SF of 3 or thereabouts you need about 1.4 to 1.5 square inches of cross section. This is the cross sectional area of a 4x2" piece of extrusion with 1/8" walls. Remember that aluminium is a maliable metal, and so any points of rotation need to be reinforced lest the holes widen themselves.

I'll stop by if I can, this week or so.