Chemistry is a vital and highly relevant field of science that is under-represented in science centers and museums. Amidst concerns that the public is ambivalent about the chemistry field, the "Explore Science: Let's Do Chemistry" project sought to understand how to design hands-on activities that could increase the feelings of interest, relevance, and self-efficacy around chemistry. Using design-based research, the team tested and refined a variety of activities while simultaneously creating a framework for future use about content and format strategies that increase interest, relevance, and self-efficacy. Science museum visitors tested these activities and were interviewed afterward to learn whether or not they had experienced any changes in their attitudes toward chemistry and what about the activity contributed to these feelings. Data indicated that the types of content embedded in an activity influence increased feelings that chemistry is relevant and interesting, while the format used in an activity contributes to increased interest and self-efficacy around chemistry. The design framework created from these findings can be used by other chemistry educators to develop additional chemistry outreach activities that support increased interest, relevance, or self-efficacy in participants.