I have a flat sheet with square cutout.  I want a flange to be bent inwards on all 4 sides of the cutout.

This would mean that each flange would have to have a 45deg cut on each end to make this physically possible.

Is there an easy way to do this?  I am currently using the edge flange and then modifying the sketch to create the 45's.  Given that my part has numerous cutouts multiplied by 4 sides each, multipled by 2 edges on each side.  Its adding up and seeming very inefficient.

I thought mitre flange would do it, but no such luck (pending Im using the command correct).  Obvioulsy I do not have the benefit of sheet metal training.