As so many limitation due to dependency of left and right hand fingers in order to sound a note, I was amazed by the great Stanley Jordan who's able to fantastically sound his guitar just by touching the strings with his both hand's fingers, so accurately fast.
He could just brake through the barriers guitarist faces like I've mentioned in the previous chapter (sub-page) as to him, he simplifies his playing by eliminating right hand plucking process and just use all fingers to tap.
Borrowing the movies' term..."He must be the choosen one", if you know what I mean ;)
(The evolution of the double guitar's design)
When I watched other YouTuber, I guessed some tapper guitarist discouraged me to play two hands tapping. They don't sound legato as I expected like the usual plucking technique, their notes sound too staccato. I don't want to sacrifice the legato sound (or any other guitar tone properties) in favor of playing more complex.
Thankfully hope rised up again when I stumbled into a YouTube video of a skillful Poland guitarist named Partyzant (Check him out!!). He played "Turkish March/Rondo a la Turka", a Classical composition by Beethoven. To me it's a impossible to play that tune with one guitar, it needs at least two guitars to play to accommodate the complexity of the contrapuntal harmony texture. But Patyzant did it well with his special "double guitar", of course with tapping technique.
So tried again to tap on a normal electric guitar just to test the possibility, it worked pretty well, I could play the guitar with only 1 hand. Since now my right hand's free, I could play the 2nd guitar. So I put a guitar on my lap and the other one on a table....I saw that "this thing" potentially could work. But of course it's very impractical to always carry 2 guitars (and a table) for a gig, a guitar with 2 fingerboards would be a good solution.
Usually all the double neck guitars made by the famous brand has very wide gap between both neck. This is because the guitarist needs to slip in his/her left hand in the gap to play the top neck (while the bottom neck is idle). I guess this' not a good idea for me, I don't see the point to have such a big gap between those necks as I want to play the top neck with my right hand from above the neck. Anyway, less gap = less weight/mass.
Since then I designed a double guitar according to my specification of need. The evolution of the double guitar's design since then began.