I received my custom tape compatible battery holders in the mail and wanted to mention the small, simple safety feature I've included in this design. 

Coin cell batteries are a swallowing hazard for young children, and if ingested must be taken to the nearest emergency centre.  In Australia, we have new product safety guidelines which state that products must now contain 'Keep out of reach of children' and 'Swallowing hazard' warnings and the battery holder must be child resistant.  There is a small screw beneath where the battery slides in to make it difficult for a child to remove, and the screw can be removed by a screwdriver.  I have used a 1.6mm hole and 1.6mm screw, but will likely move up to M3 / 3mm size to make sure that an average screwdriver will do the job.  
Alpenglow also released an interesting alternative to the coin cell battery that is still in progress, a PCB that fits in the shape of the battery.  It can daisy chain many small soldering kits together for displays and convert coin cell battery holders to run USB power.