Chord train is a simple way to explore sound, make sonic judgments, create music, and bring cohesion to a group [without too much difficulty].
We also hear these sounds commonly used.
We can use a piece of the E chord shape as a basis to build 11 other chords [we can also use the entire E shape]. The piece we are using is the root and the 5th of the chord, played together. We take a piece of E [6 and 5 strings], move the shape onto the board, and now it's movable to 11 other locations. These shapes are sometimes referred to as 'power chords'. This shape also works down a string level - 5 & 4 strings. These would be R5s based on the A form. The roots will be in different places however [think 5-0 tuning - the A5 in P5 for E, starts the cycle on the A string]. And, the shape works again on the 4 & 3 strings - these would be based on the D form.
Let's use the adding tones to a shell method to create some different modes, and put them to work. We will use Em pentatonic as the shell and add F-C, F#-C, & F#-C# (in the gaps). As E minor type scales, each of these hold one of the 3 locations for minor chords in the Major key system. [iii, vi, ii in the order below]. There are other possibilities too. We are staying within the derivatives of the Major key system.
We can also add another root to each chord. These chords are still the same name as before. The structure is R-5-R. For the fretted version, we add the pinky beneath the 3 finger.