I want to "mill out" bends for aluminum panels. I do NOT want to cut through entire SM part. I have seen a YouTube video on exactly what I wish to accomplish however it was simply pictorial and no sound nor any instructions - JUST what I wanted to do!!

Have attached the regular SW part in the flattened state. I want the 45 degree extrusions to bend at 90 degrees to have SM properties (fold & unfold). Seems after make extrusions the SM looses its properties. This particular model HAS NOT been converted to sheet metal)

Any suggestions would be great - need flattened pattern for CNC machine milling routs need to be shown as bend lines.