I just tuned up an instrument for a servicemember to GBE by request -- which is something I've never tried before and wow! So many chords, so handy!
It is a 3 string, but now I've a mind to try it with dual strings, tuned in octave pairs.
I've done that with 151 tunings (Dd-Aa-dd' for instance) but not with the GBE.
Am I a pioneer? I bet not.
Well, the Tres Cubano guitar is a double course instrument tuned Gg-cc-eE (G Major), which is close...
Yeah, I know. Stupid typing fingers...
I have seen a few I think Jason at Highwood guitars had one don't know the tuning. I will be building a mandolin soon. Fun fun
Smokestack Guitars has built several double course instruments... 3 and 4 courses. Someone's probably used standard GBE tuning... He's got lots of pics and vids up!
I had cut some "overseas grade" necks which are thicker than my usual, and I'd bet they could handle the 6 strings. Plus they are only 19" scale, so that should help with warp-resistance.
Yes, I think that, plus the Klezmitar and the Pentatonitar will be the summer projects.