I love the concept, although not a fan of non replaceable
batteries at that price point.
couple possibilities for version 2 for you;
add an optional end that has another battery in it, so you can either have a hollow one for storage as you have it now, or screw on another one instead that doubles battery life. some days you feel like wanting variety, others you know you won't be able to charge for a while and want it to last. then again, no reason the hollow cone shouldn't be able to screw on to the extra battery either, so you can have the best of both worlds, and a large aluminium baton to whack someone with at the same time. i would think an extra battery section would be smaller than the current middle section, so shouldn't be terribly larger overall.
add that extra ring of large ego style cone
threads, that way you can put on a cone to protect the thinner atomizers/cartomizers from breaking and/or damaging the threads of the
device should it fall and bend too much.
in any case, i like what you've created

if you incorporate the above two, throw me a beta to test out

lol