The 200mAh batteries should have lasted 2 hours, but the battery life proved unacceptably short.  Tested them to 1 hour of manely idle usage, at which time the transmitter was down to 3.5V & the receiver was down to 3.7V. 

They also seemed to self discharge.  They tended to always be dead after being stored. Anything bigger would require new enclosures.  Replacing the xbees with custom radios would save a lot of power.  The enclosures also need switch protectors.  The enclosures were sized to hold the switches in place.  They could be fatter everywhere except the switches, to sandwich a bigger battery next to the electronicals & give the antenna more room.

Went with translucent enclosures so the LED could be seen from both sides.  It still ended up not very visible.