Dominant 7th chords are constructed from the P1 (root), M3 (major 3rd), P5 (perfect 5th), and m7 (minor 7th) intervals of the dominant (5th scale degree) of the major scale.

dom7 chord root on 5th string

dom7 Chord – Form 5

dom7 chord root on 5th string

dom7 Chord – Form 4

dom7 chord root on 6th string

dom7 Chord – Form 3

dom7 chord root on 5th string

dom7 Chord – Form 2

dom7 chord root on 4th string

dom7 Chord – Form 1