Despite the growing potential of Internet of Things (IoT) technologies to support autonomy and inclusion, individuals with intellectual disabilities (ID) remain largely excluded from the processes of ideating and personalizing these systems. Drawing on results of participatory design studies conducted with three different toolkits, this paper presents findings from a user-centered research involving people with ID in IoT ideation and making. The results are synthesized into a set of design guidelines for accessible toolkit development, with a focus on fostering understanding, agency, and engagement. Furthermore, results emphasize the value of hybrid tangible-digital interactions in addressing physical and cognitive challenges. This paper contributes to the growing body of research on accessible computing by providing empirical evidence and actionable guidelines to democratize access to complex technical domains.