This caught my attention after watching Todd's review. Seems like a nifty little device for playing around with. I too was thinking of how to use this with a bottom fed RDA, but I have some concerns.
I'm wondering how they complete the circuit. I'd guess they use the device's body as the ground, but there is no center pin or anything (seeing as the juice bottle sits where it would be) so I'm guessing they used a little piece of wire, or a thin strip of metal which trails up the inside of the body, to make a connection with the head. I'd worry how robust the current path is for use with RDAs.