3-D Printed Carbon Fiber UAV Skin
"Carbon fiber filament" for Fused Deposition Modelling (FDM) printers doesn't have the properties you believe it does.  While perhaps a little stronger than a plain filament, in comparison to traditional items made of carbon fiber it is actually quite brittle and easily snapped, because the fibers are all chopped up into short pieces and mixed with the plastic resin.

To build something useful for an aircraft, you need fibers of meaningful unbroken length - either large pieces of cloth, or to run a continuous filament back and forth many times.

There have been thoughts of making FDM printers which would place a continuous carbon filament along with a thermoplastic "printer filament" as a binder, but that's not what a roll of "carbon fiber printer filament" gets you.  Also note that even a filament-stringing machine would only make structures which were strong in the plane the layers, but not against delamination between layers; to get a strong 3d shape like an aircraft panel, you would need a six axis machine which built in a way sensible for the shape of the component being built.

You could potentially use some ordinary or soluble filament to print a mold for conventional carbon fiber layup.