Fan blades are definitely not all 'single crystals of metal', though that is one method of manufacturing them.
Usually they are simply cast and then reworked, which produces a blade of lesser quality than the single crystal ones but they are still quite usable (and a lot cheaper!).
The newer fighter engines (F414, F119, F135) use a single piece "Blisk" fan and compressor, although I don't think its 'single crystal'. For prototyping, they can be 3D printed but are usually cast from molds and balanced for the actual engine.
Usually they are simply cast and then reworked, which produces a blade of lesser quality than the single crystal ones but they are still quite usable (and a lot cheaper!).