A beautifully minimal phone kiosk design – doesn’t include a coin-return slot.

The explicit design choice of a one-way direction of coins assumes a 100% error free connection – not unreasonably given that the coin can only be dropped once the receiver has picked up, and the conversation can only start once the coin has dropped (whether you dialed the right number is another issue).

Been thinking a lot about the design of transaction systems prior to my upcoming money project in Afghanistan, and in particular the nodes where cash enters and leaves the system.

What would it take for every coin slot in the urban environment around you to be a node in your money system? Every vending machine, parking meter and phone kiosk. And putting aside anonymity for a moment – what if every coin can be associated with a person/purchase/task/… and where putting a coin in a slot signifies the consummation of a contract between the spender and the owner of the infrastructure.