We were inspired to make uni-bumpers this year for the first time. Then our strategic design determined that we should cut the corners instead of 90 degrees. We used 1 inch steel straps bent at 23 degrees top and bottom for one joint and the other joint, 67 degrees, we counter drilled 1 1/2 inch screws into the end.
http://imgur.com/0pexG85
http://imgur.com/UWrOgGQ