I've had a similar idea too. It's a work in progress, but close to done, just waiting for the switch to come in the mail.
Two flashlights. One on the left fits an 18650 battery and the on-off safety switch that came with the flashlight. One on the right fits the momentary switch, connector, etc. It completely encloses a tank or standard size carto. I intend to use it with the smoktech's RBA tank and Vivi Nova
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As you can see, the top part of that one unscrews for tank filling or cleaning.
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I would have made it a box, but wanted it to be a bit sturdier than plastic or altoids, since I carry it in my jeans. Already broke one tank on a normal Ego -- my 8 year-old jumped on me, and I ended up with 4ml of juice in my pants
Once I'm done, I'll be working on version 2, with DNA board and a bit cleaner construction
