Double Drop D tuning
The Double Drop D tuning is the beautiful land of drone-like voicings.
Here is how you tune the guitar: DADGBD, which is almost similar to the Drop D tuning. The Double Drop D is suitable for a style somewhere between rock and singer-songwriting, for example, in the neighborhood of Neil Young, whereas Drop D is often used in rock context.
As you can notice, many chord diagrams are centered round the D tone and the key of D. But also playing in the key of G and Em would include most of the chords. The D minor key on the other hand do not partner well at all.
Concerning the G chord (5X005), notice that the three open strings actually create the G chord by their own, and therefore you could experiment by moving the lowest and highest notes. For example, 3X0003 would be a G7/F and 7X0007 would be a G/A and 9X0009 would be a G/B. As a consequence, 0X0000 would result in G/D.
Apart from the presented diagram, there is unsurprisingly many more ways to play various D chords. One example is Dm that also could be played 003230.
A more problematic chord among those often used in D major key progressions is the F# minor. There is hardly any easy fingerings at all for this chord.
A major chords in this tuning will, in general, produce a somewhat dissonant sound when the highest and/or lowest strings are included (because of the clash between C# and D notes). This is extra noticeable in chords such as Amaj7/D (002120).
For more chord charts in pdf, see Essential Chords in Double Drop D Tuning ebook linked to below.
Some suggestions of chord progressions in this tuning:
D - Dsus4 - D - Dsus4 - D
It will sound cool if you just strum the highest strings when playing Dsus4. Dsus2 could by the way be played as 000232 or, which may sound better, as 002232.
An idea with a movable shape including F and G vicings:
D5 (000230) - F6/D (000560) - G5/D (000780)
Some other progressions based on chords presented above:
Amadd4 - Em
F#m/D - Em7
Bm/D - G - Em7
This tuning is not particularly associated with blues, but here is a simple idea:
D7 (054530) - G7/D (0 10 9 10 8 0) - A7/D (0 12 11 12 10 0)
D7 (004530) - G9/D (0 0 9 10 8 0) - A7/D (0 0 11 12 10 0)
Here is some additional chords in the Double Drop D tuning listed in short notation:
Dm6: 003200 / 000203
If you want to go more into depth of this particular guitar tuning, see the Essential Chords in Double Drop D Tuning ebook with over 100 chord diagrams.
This was an introduction to the Double Drop D tuning on the guitar, see also Drop C tuning.