forget abs. Not strong ebough and does not fare well if exposed to the elements.

Forget nylon as well, not rigid enough and length of nylon that long will be really bendy.

Okay - I hate the way nobody ever explains what they actually mean in imperial measurements.

Am I right in thinking you want to make 8, 1 foot lengths that are 6 inches wide by 2 inches thick ?

In what orientation will the beams be used ?
If vertical then nylon would probably work.

A 2 inch by 6 inch beam of almost any 3d printer filament will be sufficiently rigid fo the job.

Pet-g would work well, as would pla. 3d printed abs isn't great and really doesn't fare well outside.
If you can afford that much nylon, then it would work too.

what printer do you have ?