The most common (and affordable) cantilever/tip assembly is made by a process borrowed from microelectronics:
Thin layers of material are deposited on top of a silicon crystal that has been shaped into a small cantilever. A micro-photographic process then creates a single small dot of protective coating. The whole assembly is then exposed to an etch. The surface etches downward except where it is covered by the dot. Under the dot, this leaves an extremely small tapering column of untouched material. Stronger and sharper tips (using, for instance, carbon nanotubes) may be used but these can cost ten times as much.