I figured a thread dedicated to the most important safety item in an off-road vehicle was needed.
a few basics on building roll cages
you can use sch40 also known as poop-pipe but it is not recomended and you will die
I like to use either DOM or HREW structural tubing, it is designed to be structural not to carry fluid/liquids. I use 1-3/4" but it really depends on what dies are available for the bender you will be using.
I figured that I would post some pictures of the Toyota cage that I am building at work and some others to give some ideas of how to build a roll-cage that both looks nice and will protect you in a roll over.
Some designs will be very simple and other more elaborate but always remember triangulation is your best friend in roll cage construction.
here is my bender
and the begining of the Toyota cage the double B-pillars
oh and it fits in a standard cab truck