Very nice! Is that a long 510 to 510 adapter or something else rigged up?
That is awesome. So did you just put 510 connection in the top of the carto that is in the tank?
Due to some work I did with DD early on, I had a spare brass ring sitting around. So...
I press fit a 510 connector into it and used a rotary cutting wheel to slot the sides to match the coin slots on the ring.
The bottom is just a standard Boge cartomizer that was sacrificed and gutted for the occasion.
The carto center pin was pulled out, and a length of hobby wire (probably 14 or 16ga?) with a short coil in it (just for some spare length) went through the carto body.
The carto center pin was soldered to the wire and re-seated in the body.
The top of the wire was soldered to the center pin of the connector in the brass ring.
The carto body and ring are not (currently) physically connected together, other than by the wire.
This gives a bit of freedom to make sure the bottom of the cart is centered over the positive pin in the BB before snugging down the brass ring/atty connector.
The diameter of the atty connector (on the underside of the brass ring) is smaller than the carto body, so it drops inside the carto body while the brass ring pushes down on the body itself to make the ground connection.
Et voila!
It's not as easy to drop in as a tank and can't really be put into a tank body as-is because of the wire connection to the brass ring/atty connector.
If I had the time, pieces/parts and some extra machinery lying around, I think it would be possible to make a spring-loaded center post for the inside of the cartomizer body to mate with the center post of the atty/brass ring when it's snugged down. That way the carto adapter could be fit into a spare tank (for easier installation and internal alignment) and wouldn't require the hard-wire connection.
Still, for a proof-of-concept, I'm happy with it.