Basically a Baritone has a longer scale length (27”-30.5”) & a larger string gauge (.012-.60/.013-.64/.014-.68) and the obvious of being tuned lower? Made my mine jus like a regular cbg, but with a longer 28.5” scale, ez peasy?
Did you make the neck any thicker? Right now I'm shooting for !"-ish without fretboard installed...
Standard red oak neck-thru cbg neck w/ heel, strings 4, 5, 6 from a heavy gauge set. I built it 16-17 yrs ago & it’s only got a tiny warp from leaving it in pitch too long without playing it? You can also go full Baritone like a traditional Bajo Sexto, with a larger , deeper box if you want more Bass & growl to it? The next one I build will either have a truss-rod or carbon fiber rod in the neck, I want to use a .068 for the low string, which is pretty much a D string from a Bass, so I’ll need it for rigidity? Good luck on this, have you searched the site for any info?
Also, Shane built a 3 string Baritone with a Broomstick, so I think you’re good? I think there’s a video of it in the “Featured” section?