Chili, for the Subtank "mini" I have just either recoiled an old casing or recoiled an old Aspire BVC replacement casing with two opposite holes drilled out 5/64th bit. I haven't much used the RBA for the Subtank. Been slow in perfecting the coil for that.
The 5 ml Nauty I've had hubby drill out two opposite holes 5/64th on an old Nauty casing too. Since the largest hole on the AFC of this size Nauty was too restrictive for me, had him drill same size large hole opposite the largest on the AFC. Can't adjust it any more, but now got enough air for me.
Essentially what I've done is convert them to tootle puffing with a single horizontal coil. 30 gauge Kanthal, 7 wraps, spaced, wicked with cellu cotton, fluffy bunny tails on either side of casing. Pretty basic and not for high watts.
Believe there's a video out there to recoil a Nauty vertical. Can't remember tho who did it........Rip Tripper!