Bioengineering represents an interdisciplinary field with the potential to engage young learners in science inquiry and engineering design in the context of real-world challenges. Although children encounter bioengineered products and solutions in their everyday lives, they are not introduced to bioengineering until much later in school, after stereotype threats about STEM engagement have crystallized. The purpose of this paper is to present an experimental tangible tool called CRISPEE and evidence from an intervention with young children who explored CRISPEE in the context of an informal bioengineering curriculum. In this design study, 25 children aged 4-7 years engaged in a 9-h workshop designed to introduce them to foundational bioengineering concepts of gene editing, engineering design, and bioethics. Children's attitudes and content knowledge about life science, engineering, and bioengineering were assessed pre- and post-interventions. Mixed quantitative and qualitative results show that most children entered the intervention with pre-existing ideas about genes and attitudes about engineering and science. Post intervention, children demonstrated increased positive STEM attitudes and content knowledge, especially in the area of science inquiry, and also demonstrated an emerging curiosity about the purpose and effectiveness of bioengineering work, including bioethics. Implications for research and practice are discussed.