  We determine the inducibility of all tournaments with at most $4$ vertices
together with the extremal constructions. The $4$-vertex tournament containing
an oriented $C_3$ and one source vertex has a particularly interesting extremal
construction. It is an unbalanced blow-up of an edge, where the sink vertex is
replaced by a quasi-random tournament and the source vertex is iteratively
replaced by a copy of the construction itself.
