Tapping buttons and hyperlinks on smartphones is a fundamental operation, but users sometimes fail to tap user-interface (UI) elements. Such mistakes degrade usability, and thus it is important for designers to configure UI elements so that users can accurately select them. To support designers in setting a UI element with an intended tap success rate, we developed a plugin for Figma, which is modern software for developing webpages and applications for smartphones, based on our previously launched web-based application, Tappy. This plugin converts the size of a UI element from pixels to mm and then computes the tap success rates based on the Dual Gaussian Distribution Model. We have made this plugin freely available to external users, so readers can install the Tappy plugin for Figma by visiting its installation page (https://www.figma.com/community/plugin/1425006564066437139/tappy) or from their desktop Figma software.