[Bob Thompson]

Not to put a pin to your balloon, but carbon fiber is at an all time high in price. Boeing has virtually cornered the market on the stuff for use in is latest passenger plane offerings. Going one step beyond that, carbon fiber is very electrolitically active meaning it causes things to corrode big time including 316 stainless steel which is the stainless for saltwater applications. The key is to isolate the carbon fiber from everything else with other materials which are not electrolitically active like S-glass or E-glass. Since cabinets do not need the "extreme performance" of carbon fiber, you might consider using "S-glass" which is much cheaper and performs at about 55% of carbon fiber. Or, you could use standard "e-glass" which is waaaaaaaay strong enough for cabinets and with colored "e-glass" or colored resins you can get the "black" carbon fiber look. Sandwich the E-glass up with pvc foams and you will have super strong cabinets which will weigh about 15% of wood cabinets.

If I were doing it, I'd use wood at the corners for ease of construction and joinery and colored e-glass/pvc foam panels (not necessarily black) in place of plywood. It would be affordable, very light weight, and extremely strong! Plus it could be made to look fantastic, and it wouldn't cause things to corrode.

Or..... you could go a much simpler route and just replace all your plywood shelves with 1/2" twinwall polycarbonate panels, as I did, and have plenty of strength for shelves, the toughness of polycarbonate, ease of construction, reasonably low cost, and very low weight.