[MrForbes]

Aluminum weighs about 1/10 of a pound per cubic inch. So, if you had a 3" x 1/8" x 36" side rail, without any holes, it would weigh about 1.3 lbs. Two would weigh 2.7 lbs. That's not very heavy. But they probably ought to be made of an extruded or bent shape, such as channel or tube, to have the necessary resistance to bending.