If you are developing any electronics project, probably you wanna prototype first to make sure it works as expected before building real boards. Low power electronics usually relies on smaller batteries – especially wearable, mobile where size matters. In this case you usually choose a button cell battery. When prototyping probably it is good idea to use same battery in breadboard. Question is how to attach it reliably to breadboard.
Grathio labs provided a simple solution that saves time and money. They suggest to make coin battery holder out of binder clip that you can find in any office. This solution can be used to house one or several batteries depending on width of clip. Also it could fit different width batteries. Great idea can be so simple use it.