One of the most popular types of Spring Pins are the Slotted Type. These manufactured to DIN 1481 standards.

These Spring Pins are manufactured with a slight larged outside diameter to that of the hole size. The slot enables the spring pin to then close down to the required hole size and will be able to slot inside.

You can but these Spring Pins Online, next day delivery available. Please use this link to view the range: https://springfasteners.co.uk/product-category/engineering-pins/spring-tension-pins-din1481/