I'm not 100% sure if all 510's are the same as I'm a newb, but ZigCigs.com sells a PCC that will carry 1 battery, 1 atty, and 2 carts. Also, it's a charging case so it will also charge it for you when ur on the go. Not a bulky item, more like the size of a pack of Misty 120's. But, the downfall is it's not really a "carrying case" since you have to disassemble and reassemble ur pv everytime you want to put it in there. Works well for me as I usually carry 1 as a backup to get me
thru the day. It would be nice to have one that had a spot big enough to hold an assembled unit and also one to charge tho...