Two of my favorite 14500 mechanical mods are the 16mm GP Piccolo v4 and the 17mm Atmomixani Nemi (14500 or 14650). I use the new 650mAh AW 14500 batteries - their max CDR is 9A, so you don't have a lot of headroom for a .5ohm coil at 4.2v (I don't sub ohm, so I don't worry about it). Efest makes a 14650 battery that probably has a higher amp rating and at 950mAh will last longer in the Nemi.