PATTERN FOR DOCTOR BAG

I’ve been asked to make a very special present for someone. It’s a travel bag/doctor bag, although with two loops handles instead of the single rigid handle. The frame is 20” x 5” - much larger than the normal I think. I accept that it is unlikely that there is a pattern for exactly that size (I could only hope) but does anyone know of a pattern that could be easily multiplied to reach the size I need? Thanks in advance