Well, here's the finished prototype:
That top cap is the .... end of a dead flashlight, it's way too thick because my wiring method was designed to be easy to change on the fly while I worked things out, and there's a lot of excess wire and heatshrink that has nowhere else to go.
Notice the amber LED, that tells you it's operational (actually sending power to the RCA fitting:
If the safety switch is engaged, triggering the button lights a green LED and no power goes to the RCA fitting:
And here's the basis of the next model:
I won't need to run wires outside the bowl except for the battery fitting (I'm going to use strips of ribbon cable from an old black IDE cable, now that all my drives are SATA, I have a bunch laying around). The top will be capped off with a rubber pad and a large brass washer, I'll be putting the switch on the side under the index finger instead of under the thumb. The combination will let me reduce my form factor for the cap to around 1/4 of an inch (rather than the full inch it is now).
The battery pack you see there is a keychain pill bottle with the fob portion removed, this one is red because that's what I had lying around, future versions will be silver (cheaper and better looking), black if I can find a paint that will stick reliably. I'll use a single LED for status, red for safe mode and green or amber for operational. I don't like the way the safety switch I used looks, so much so I didn't even take a picture from an angle that would show it. I'll keep the switch in the design, but come up with something much more polished. Functionally the prototype is great, I vaped all day (2ml worth or so) and used only half the battery capacity. I'll need to make a custom charger, as making the battery removable independently complicated assembly too much, I don't want a potentially unprotected cell feeding this, and it loses the idiot-proof functionality of the connector.
Even as an ugly hacked-together prototype, this would do better on the "would you want to take this through airport security" test than the sonic screwdriver, pipe bomb, and battery case mods that are the standard these days. The new model will be much sleeker and polished, and it will keep the significant features; safety switch, indicator light, large 1200mAh battery, and a safety vent for the cell that points the positive end down). If the battery goes into thermal runaway and started venting, a little plug of hot glue will get popped out and release the pressure (otherwise, what I've got there isn't a battery pack as much as a small incendiary grenade, even with a protection PCB).
--Dave
