Here is the umbrella anchor attached to the body of my Spikor rocket. A tube from a CTI 29mm reload fit nicely in the anchor. I cut a hole to allow the retention screw to be fully inserted. A Kevlar cord is looped around the screw hole and was epoxied to the inside of that tube. To mate with the body, a piece of 38mm tube was glued on and a sectioned piece of another paper tube glued on top of that.
I drilled holes in the auger bit to allow a 1/4" rod to slide through. The Spikor came complete with rail buttons...but no rails for this one. I added an extra metal lug to help it keep going straight.
I will need some encouragement to put a motor in this beast. If you don't have anything good to say...say it anyway ;) I may add some sort of roll pattern if the launch decision approaches the GO state.