Here is my latest effort... the NanoGen!
It's powered by an external battery (ideally to be housed in a small cigarette lighter). It's smaller than the smallest ecig - but holds plenty of juice (compared for size here to an M401).
The coil end remains exposed and the vapour is drawn down through the device to the mouthpiece.
(I like it when the tip glows hot and smokes like a real ciggy

. I'll use a pen cap to protect the coil when in transport - although at the moment, it's actually retractable down into the metal tubing by twisting the other end!).
I have used ceramic fuses to hold the wick - which I highly recommend (as they can be surrounded with a less critical material to fit within any tube, and are very cheap).
A flexible plastic tube (from a soap dispensing bottle) fits perfectly on the end of the ceramic fuse and this houses the rest of the wick. I have used a smaller section of the tube as a washer to hold the wires in place at the top. The wick is about 1.5mm thick.
The whole thing then slides neatly into a section of antenna - with enough surrounding space for air intake.
The plastic tube is sealed with a rubber stopper (removable for refilling). Over this slides a (temporary) mouthpiece.
It all works and makes a decent amount of vapour. I am now waiting for my nichrome wire to be delivered so I can make a new, tighter and longer coil (this one uses the coil from an E2) and get a bigger blast.