The Pay-with-a-Group-Selfie (PGS) project, funded by the Melinda & Bill Gates Foundation, has developed a micro-payment system that supports everyday small transactions by extending the reach of, rather than substituting, existing payment frameworks. In an effort to embed a digital wallet to the PGS, we analysed the system architecture that will be needed and the requirements drive us to opting for blockchain based architecture. We have presented the applicability of a blockchain as platform in a previous paper. The current paper is presenting the functional requirements, the platforms needed for the development as well as the prototypes of the major interfaces.