Source for cheapest carbon fiber sheets?
How do you fill a carbon plate with tow and epoxy and have it weigh less than air? Honeycomb is mostly air. The cells are not filled with epoxy. Also, tow is just unbraided carbon fiber so the weight of 0.125in of carbon layup is as I said above: about 10 layers thick of 10 oz/sq yd. for a total of 100 oz/sq yd. A honeycomb sandwich 0.125 in thick as I described above would weigh about 27 oz sq yd. and would be more than stiff enough for any RC fuselage.
Also, carbon is about $4/sq. ft. so making a 0.125 plate would cost about $40 sq. ft. A honeycomb sandwich would be about $24 sq./ft. If balsa were used as the core instead of honeycomb, you are at about $9 sq. ft. Of course you could just switch to glass and it is much cheaper still, and plenty strong.