Well... look at the cross section of a dragon fly's wing... or a butter fly.... hardly a precision structure from a uniformity standpoint. But the structures irregularity does kinda ensure a turbulent flow... these guys are not always flapping you know... I have on many occassions watched them just glide along.

Actually, depending on what you consider accurate... I have available machine shop tools (CNC mills, Lathes etc) and sufficient molding and composite skills that I could make something in the plus'r'minus range of about .005"... but I agee with you... it is not worth it!!!!