This article explains the analytical process through which the Reserve Bank established technical specifications for New Zealand’s recently issued silver- and copper-coloured coins. The new coins are smaller and are constructed using metal plating rather than solid alloy. Both these innovations reduced the cost of manufacturing New Zealand’s coins, but also required extensive testing and analysis to meet the needs of the vending machine industry and the general public. In particular, the Reserve Bank needed to be satisfied that the coins could work reliably in vending machines, yet also be hard to fake. The coins also had to withstand the wear they would be likely to receive in circulation.