Four strings for a guitarist,is either a vacation or a robbery in progress. 
Tenor banjo tuned ,C(A(D(G( offers some "reverse Peep holes" (I'm a Seinfeld fan) 
on a brain that's wired E(B(G(D(A(E .The triadic Intervals transfer  from
each adjacent pair of strings in a parallel manner.
 The four main chord types are :
~~Major (M) Minor(m , -) Augmented (+),and Diminished (dim7)~~

  Observe ` Third M\m, or 10th interval (when on G , D, orA ).
  N.B., for later developments now, rest 1rst finger on nut.

~~   ( C Major)~     (~ CMinor~)~       ~(C Minor)~    ~(C dim = Adim=F#dim=Ebdim)
      R 5 3 Oct       R 5 3 Oct          `3 R 5 Oct       `3/7/5 R (C)
~Nut |C|G|D|A|~     ~|C|G|D|A|~         ~|C|G|D|A|~      ~|C|G|D|A|~
fret1| | |`|-|       | | |2|-|     /fret3|1|-|-|1|   fret2|-|1|-|-|
fret2| | |3|-|       | | |`|-|    / fret4| |-|-| | \ fret3|2|-|-|3|
fret3| | | |4|       | | | |4|   /  fret5| |3|4| |  \fret4| | |4| |
~    (_______)       (_______)~         ~(_______)~      ~(_______)~
~      !+!
~  (C+)= (E+)=(Ab+)
      R+5 3 Oct
~Nut |C|G|D|A|  
Fret1| |2|-|-|
fret2| | |3|-|
fret3| | | |4|
~   ~(_______)~
~play: CM,C+ to FM
~            \\   
              ~  F Major        ~ FMinor  ~
                    5 3 R 5       5`3 R 5
              ~ nut|C|G|D|A|~   ~|C|G|D|A|~
              Fret1| |-|-|-|     | |2|-|-|Fret1
              fret2| |3|-|-|     | | |-|-|fret2
              fret3| | |4|4|     | | |4|4|fret3
              ~   ~(_______)~   ~(_______)~
              ~    (+)
              ~  F Augmented 5~
              ~    +5 3 R +5 0= open Option
              ~ nut|C|G|D|A|~
              Fret1|1|-|-|0|
              fret2| |2|-|0|
              fret3| | |3|0|
              fret4| | | |4|
              ~   ~(_______)~
              ~play FM ,F+ to BbM
                            \\
                            ~    Bb Major     ~ BbMinor~
                            ~     3 R 5 Oct    `3 R 5 Oct
                            ~ nut|C|G|D|A|~   ~|C|G|D|A|
                            Fret1|-|-|-|1|     |1|-|-|1|
                            fret2|2|-|-| |     | |-|-| |
                            fret3| |3|4| |     | |3|4| |
                            ~   ~(_______)~   ~(_______)~
                            ~
  See also Guitalife's  Tenor Banjo