Symmetric scales
A Diminished (Half-Whole)
The dominant version - jazz players put it over 7b9 chords.
Notes
How to get there
Eight notes alternating half-whole; the whole-half scale from a step below.
On your instrument
Tap any note to hear it. ● root ● scale note
Guitar - Standard (EADGBE)
Chords in this scale
This scale skips too many steps to stack tidy thirds - treat any of its notes as colours over the drone instead of building chords.