Formula 1 b3 5 b7, so Cm7 is C Eb G Bb i.e. 8653xx
Here are the 5 basic CAGED shapes for a m7 chord:
Cm7: x31313
Am7: x02010
Gm7: 310031
Em7: 020000
Dm7: xx0211
and here are all the playable open-position minor 7th chords I can think of which use open strings for their 1, b3, 5 or b7
Am7: x02010 or x02013 or x02213
Bm7: x20202
Cm7: x3x046 or x35046 (not really open-position, you have to cheat to get the open 3rd string in)
C#m7: x42100 or x42400 or x4x420 or x42104 or x42404
Dm7: xx0211
Em7: 020000 or 022030 or 022033 or 020030 or 020033 or 020003
F#m7: 202220 or 2x4220 or 204220
Gm7: 310031 or 3x0331
G#m7: 4x1102 or 4x1x02 or 4x1402
Comments
I only recently noticed these posts, @bigjon; I love 'em! It's great playing through these lists of chords because although I have discovered most of them independently (been going a long time), I probably haven't thought about the name of the chord and what that means.
Less GAS, more TAS (theory acqusition syndrome).