Composite question OT

I noticed a recent discussion about materials used for the
construction of Sailplanes. I am looking for a material to help
support a weak area on the cowl of an airplane that I fly. It is a
power plane (has one of those fuel to noise converters) so please
forgive.

The cowl is wide and the center is starting to droop and crack. I am
tring to find a material (honeycomb?) that is about 1/4 to 3/8th inch
thick that I could glass in or use epoxy resin to stiffen the cowl. I
am looking for something a bit more structural than layers of
fibreglass. I would like for it to be light and thin enough that it
does not distrub the airflow inside the cowl. I am looking for
something in the range of 4 inches wide by 3 ft long to glass inside
the cowl to help support it. It will need to be flexible enough to go
around a few minor curves.

Thanks in advance for any suggestions from folks that work with
composite materials.

Take Care
Steve