While smartphones have positively transformed how we live, work, and communicate, concerns about their impact on individual wellbeing have driven research toward solutions that promote more intentional and mindful usage. In this context, Digital Self-Control Tools (DSCTs) aim to help users regulate their technology consumption, but their interventions often remain rigid, offering limited customization and treating users as passive recipients rather than active creators of their own digital wellbeing strategies. To address these limitations, this work explores the intersection of End-User Development (EUD) and DSCTs, aiming to empower users to design and personalize interventions that suit their individual needs. We first created an Event-Condition-Action (ECA) framework consisting of unique events, conditions, and actions, based on a state-of-the-art taxonomy of DSCT intervention strategies. Then, we developed a mobile application to evaluate the understandability of the framework and the usability of a rule-creation interface built upon it. A usability study with 11 participants revealed that users found the approach understandable and the app highly usable, with an average SUS score of 82.5. These findings underscore the potential of combining EUD with digital self-control interventions to create tailored and user-centered DSCT solutions.