Font BuildFont( FontFamily family, float size, FontStyle style )
Function BuildFont ( family As FontFamily, size As Single, style As FontStyle ) As Font
It is expected that an implementation of IFontBuilder will only create any unique font once, no matter how many times it is called with the same parameters. Any mechanism for caching is left up to the implementor.
Although it is possible to return a font which is a different FontFamily or FontStyle as that requested, that process is mapping and should be handled by an object that impements the IFontMapper interface.