To attach wings I usually drill 2 holes in the box sides and screw into the wings from the inside of the box. Depending on the thickness/integrity of the box, sometimes I've used washers on the screws and other times a wood stiffener inside the box.
Yes, if you use an open tuning with a minor third, it is easy to fret that note to return to a major third. This is what the old Blues masters called "Cross note tuning". Instead of Open D (DADf#ad), they tuned Open D minor (DADfad). This gives you the same advantage as standard tuning, when playing for example an E chord. The open third string is the minor third - G, playing the chord adds the major third - G#. By playing between them, you create that typical minor / major tension found in the Blues.
As for three string CBG, I found a 513 works out really well for movable chords. This is the subject of my instructional video #6.
A 153 tuning is actually quite unique in regards to the usual open tuning tone arrangements.
Thanks for sharing some more of the endless possibilities. Enjoy your practice, Keni Lee
Thank you for sharing Sam. I mainly listed major tuning variations in regard to string number. Yes, tuning the 3rd down a half step makes a very inspirational difference. It always amazes me, how powerful that one little note is. That tension created between major and minor tthird is probably the source of most of the Blues sound. Shane demonstrated in his video the altering of the first tone. 151 down to 15(flat 7) and 151 up to 159 (basically the 2nd in the next octave). There truely are no rules because the possibilities are almost limitless. Enjoy your practice, Keni Lee