1519 has never bent aluminum box/tubing of that size manually... In 2008 we used 1x1x1/16" box as the curved "tusks" to hold the large trackballs, but these were formed by a machine shop for us. (For a picture of that robot, we have some pictures on our website:
http://mechanicalmayhem.org/Mechanic...agegallery.php)
We have also used a pipe bender (vaguely similar to this:
http://www.harborfreight.com/1-2-hal...der-94623.html) successfully to bend fairly small (.375-.75") square or round tubing of either aluminum or steel. It's a forming method that can be very useful, but also somewhat imprecise and tedious.
Basically, I'm not sure that it can be done with hand tools or simple fixtures, but machine shops have the equipment to bend tubing profiles far larger than 1.5x1.5. It looks like a fairly simple hydraulic press like this (
http://www.harborfreight.com/16-ton-...der-35336.html) can bend round profiles, but I'm not sure how a square profile would behave.