RE: Carbon fiber chassis ?'s
holeshot makes them. they sent me a bulked up version after I had a similair problem.
though I fear it may just be one of those parts that needs some flex to absorb landings, being that it is such a thin area. holeshot says they strengthened it though.
as for making it yourself, I donno. ussually they make it with a water jet, to rather precise dimensions.