.. to me and my way of thinking, two necks wanna be played together in the same tune in order to justify sharing a body. Otherwise they may as well be two guitars if you know what I mean. So in terms of 3 string guitars presumably in an open tuning, id want them in the same key as each other.
I'd be asking if you can fit bass sized tuners on one of the heads, or if you can fit double tuners (i.e. 6) so you can do one with octave pairs like a 12 string guitar
Thanks ''Phrygian Kid'' firstly for confirming my original thoughts on both necks being tuned to same key, and secondly for the idea of a 3 string double octave on one the necks, this build (a pic soon to be posted) was originally going to have tone, volume & 3 way switch added, but the size of the box was a bit small, so it just has the pup's wired directly to the output jack, there will be further twin necks built in the near future with all the "Bells and Whistles" with a larger Cigar Box or Homemade Box.