Re: Boolean: opposite of A intersect B

For future reference, here are a couple other ways you could go about it:

1. Create two identical circle splines. Use the Mesh>Spline>Project command to project one of them against a plane or cube rotated to 45 degrees. Use a loftNurbs to loft the two splines together;

2. Create a cylinder and make it editable. Use the knife tool in line mode to cut a 45 degree edge loop into the cylinder (holding down shift restricts to 0 and 45 degrees). Delete the unwanted polygons and then use the "close polygon hole" command to create a new cap.