A mold assembly for soles of footwear includes a first portion having first and second recesses, and a second portion having first and second projections. The first projection is received in the first recess to define a first cavity for a first sole and the second projection is received in the second recess to define a second cavity for a second sole when the second portion and first portion are mated together. A first removable insert forms at least a substantial portion of a medial side wall of the first recess and defines an exterior surface of a medial side wall of a first sole formed in the first cavity. A second removable insert forms at least a substantial portion of a medial side wall of the second recess and defines an exterior surface of a medial side wall of a second sole formed in the second cavity.