There is also room in the XL to go ahead and suggest a filler port, which is a hole on the side of the carto, bigger than a 901 hole, that the little hobby oiler bottles can be used so that syringes are not required.
Scottbee made one like that, I think, but I haven't seen pics, are they on ECF Scottbee? Is there a design you would think could work on the XL cartos?
A ring on the carto of some sort could be somehow locked in place, until it's time to fill and re-fill. The ring then is unlocked lengthwise, and then rotated or spun in one direction to unseal and reveal the filler port?
I'm not sure that would make a good seal when the port does not need to be accessed, though. Any thoughts?
Something like this might be for a future ce3, and they can even make them 1mm wider in diameter. The wicks would not need to make a sharp 90 degree turn right as they come out of the slots either, and the carto could hold almost another ml.
Regular 280mah 808d batteries, and the regular 510megas, could also be made just 1mm wider. That is not that much a difference, but yet enough that could help many things. I'm thinking of batteries more narrow than the vgo, but slightly longer. Right now the vgo battery is much shorter than regular ecigarette batteries, but so much wider.