Additive manufacturing (AM) continues to play an important role in product development, and many companies are searching for how to best integrate AM into their products, business models, and design processes. Often, AM is integrated into later stages of the design process for products during manufacturing and production. However, there is an opportunity to introduce AM in early-stage design, which could spark new business models and services in addition to re-thinking manufacturing for products. The central research question for this paper is what is an appropriate and useful tool to support innovations with AM early in the design process? Prior work has extracted and validated AM design principles. This paper describes the strategic development of AM Principle Cards from these design principles. The cards are a vehicle for codified AM design principles to be shared and understood in a way that inspires learning, creativity, and AM considerations during the early stages of the design process. They implement a number of best-known practices from an inductive principle-extraction study and literature related to the use of design stimuli, learning theory, design by analogy, and creativity. The AM cards were awarded a Singapore Good Design Award (SG Mark) for 2019. The AM Principle Cards were validated in two studies. In this paper, an ideation study is conducted with 85 designers to elicit feedback about the cards’ effectiveness to explain concepts related to AM and their ability to inspire creativity and new innovations. An additional ideation study was conducted with 61 participants that showed significant improvement in quality and novelty of ideas. The full deck of the final 27 AM Principle Cards is shared for design educators and practitioners to use.