The Coin Cell Maestro facilitates use of different sized coin cell batteries. The radial and 90 degree offset of the holes accomodates 4 different sized batteries: 6mm, 11mm, 16mm and 20mm. Please see the component list to find the corresponding clip for your sized battery.
You can purchase the Coin Cell Maestro board off the tindie page link in the Links section.
i really like your concept. Mind if I make a Pure modules compatible module.