You're probably not gonna find anyone with a 3" die. Make some rock sliders out of 2x4 3/16" rect. tubing. If you are going to use them for anything other than steps then you want to go atleast 3/16" thick.
Besides...3" tubing is sooooo early 90's.
You "MAY" i f you're lucky find someone at a muffler shop or diesel shop to bend that large of a tube but it could distort at the bends you'll just have to try a piece and see