Whats your kink?

hey guys, my friends and i are planing on havin a couple rails made for this winter, we're goin to buy a bunch of 2x4 and 2x6 bars of steel. one of us know can weld fine so we're planing on renting a arc welder and building them at my house so we have a mini jib park for the winter. So we shere designing the rails we wanted but we wernt quite sure what the angle of the kinks should be (the kink in a down flat). we where thinkin anywhere from 15-30 degrees (165-150). what have others done? what is the range at parks? thx.