This chapter proposes that the manifold tinkering and experimenting that happens in and around markets and their infrastructures over time holds valuable lessons for the future design of these markets. More specifically, we argue that a fair and equitable market design can only be achieved if the legal and political mechanisms that have shaped that particular market over time are understood, and misfires and repair attempts of the past are acknowledged and reflected upon. Using a historical perspective, this chapter maps the decades-long tinkering behind the HIV medications market, a market that has historically misfired in and through its very blueprint, which is strongly framed by its legal infrastructures. To examine the experiments in this particular market to create a collective good, we trace the relevant laws, property rights provisions and amendments, market governance practices, and civil society actions over the past forty years. Reflecting on the many misfires of this market and the equally numerous attempts to repair it, our study considers market tinkering as a reaction to overflows as an iterative, experimental process, but one that is likely to never fully transcend the market’s formative blueprint. Ending on an optimistic note, though, we also think through ways of radically redesigning the market for essential medicines.