Cost of materials is 30-50% more than pure bidirectional e-glass if I use the minimum layers of carbon and have double the glass layers, biggest thing is building molds...I found that weight was double or more with straight glass just because I could use way less material with carbon. I used an e-glass cloth layer between the layers of carbon which helped save cost and the carbon was so much stiffer than glass when it is separated with layers glass, glass parts were .040-.125 thick, carbon .020-.030 with a layer of glass in between the carbon. These were not overly large parts, just farings but weight adds up quickly on an aircraft. Tim

Bagging made a huge difference in weight vs just a gel coated wet layup with chopped matt or heavy glass cloth to get the same stiffness.