Use this Calculator to figure the length of C.  Once you have this length the Shape Editor is easy to use.  In the Shape Editor always work counter clock wise.

When putting on doors or doors and face frame rotate the cabinet so C is going right and left not at an angle.  Attach doors or doors and face frame.  Then rotate back 45 degrees.

The cabinet is easy to create or modify if you follow these simple rules.

You can also make the side edges 45 degrees if you want.