The continuous spread of additive manufacturing also raises the question of what procedure to recommend when changing the manufacturing method of already constructed parts from injection molding to additive manufacturing. To answer this question, the differences between the two manufacturing processes and the respective end products are first presented. Based on this presentation, a concept for the adaptation of the CAD models affected by the changeover is developed. The goal is a procedural change that is as complication-free as possible. At the end, the finished concept will be reviewed in terms of its utility and its applicability to a specific example. In addition, a boundary between the CAD model adaptation and a new design of the components is drawn in the sense of a stress-related design.