It seems it's already for sale in Germany: eRoll PCC Mega
The battery of the PCC must be very flat that it can fit in there.
Want Want:
Parameters of joyetech Eroll PCC :
Performance 3400 mAh battery
Input Voltage DC 5 V, 400 mA
Output Voltage DC 5V , 200 mA
Length 10.8 cm
Width 4.8 cm
Depth of 1.3 cm
Weight about 90 g
Charging via USB connection
Practical magnetic closure