The article examines how dwellers in Kenya’s informal settlements engage in continuous tinkering of a particular grassroots infrastructure: local currencies. The article argues that the malleability of these grassroots infrastructures enables grassroots networks to actively and creatively engage in reclaiming and reorganizing money, a critical infrastructure. The argument is built in three steps. First, it presents the notion of money as an infrastructure and local currencies as grassroots infrastructures. Second, it follows the development of the Kenyan local currencies from paper- to blockchain-based, and identifies malleability as a key trait of small-scale grassroots infrastructures. Third, it highlights the extent to which malleability enables grassroots networks to engage proactively and creatively with the city through tinkering practices that continuously adapt these local infrastructures to the community using them. The article ends with a discussion of the implications of grassroots monetary infrastructures for the understanding of urban politics within urban studies.