Normal, everyday clothes pins can be useful when it come to modeling. They can be used on large scale models for rivets for example. It is becoming more common for the mecha modeler to incorporate pins, beads and the like into their build to enhance the look of the kit.
In this tutorial, I explain how to mount a pin into a piece so that it is flush with the surrounding area.
Link:
http://www.ghostofzeon.com/diy/detailing/pinmounting.htmlNote that this method isn't just for pins - you can use the exact same method when mounting beads or IC pins for example.