Take a piece of posterboard, or a manilla file folder, and draw a 1-1/2" belt through the middle of it. Make a dot in the middle of the lower belt line. put the bottom center of the protractor on that dot. At the top of the protractor is 90 degrees. To get a 15 degree cant, you'll make a mark at the 75 degree place for right hand, or 105 degree for left hand. Using a straightedge, draw a line from this mark to the mark you made on the bottom line of the belt you drew. This line is the correct plane for the top of your pistol slide or barrel. Now you can lay your pistol on the drawn belt where you'd like it to ride, with the top of the slide/barrel on this line. draw an outline of the pistol. Now you simply draw your holster around the pistol's outline. Hope this helps.