Carbon fiber filament arrives today and I wanted to see if this stuff is REALLY twice as stiff as ABS. I am building a simple test stand to determine young's modulus of Proto Pasta's 15% short fiber pla. Will post results. Update I printed the carbon fiber ISO specimen at 200C on a clean glass bed at 60C. Adhesion was perfect and it did not warp at all. Contrast that with the regular PLA sample that lifted slightly on both ends. (After all the aspect ratio is quite high) Results Black PLA - 3.312 GPa Carbon Fiber PLA 5.248 GPa CF version is ~60% stiffer Proto Pasta has a value that is a bit higher, I expected to have some error because of how flimsy my bootleg setup was. I believe that the published value of 6.5 GPa is right on. I think this has some great uses on rep rap designs (optimized I-beam for delta bots anyone?) and definitely quadcopter trusses/airplane wings. However, be aware of how brittle this filament is. It breaks cleanly and suddenly with no stress whitening. It is not well suited to take impacts. -Michael I am printing 3mm filament with a .5mm nozzle. .4mm layer (10 layers) 5 perimeters 100% rectilinear fill sllllloooowwww, I dont want delamination to be the primary failure