Shaping by Touch
The touch that isn't a strum
The touchpad Touchpad reads direction. A finger moving along the strings is a strum. A finger moving across them - the other axis - plucks nothing at all. It shapes.
Riding the level
While a shaping finger rests on the pad, its position across the strings sets how loudly the whole ringing chord sits. Slide toward one edge and the chord swells; slide to the far edge and it fades all the way to silence; slide back and it returns. The chord's balance never changes - every string moves together, so it behaves like a hand on the instrument's level, not like six separate faders.
Lift the finger and the chord goes back to fading on its own, from wherever you left it.
Colouring the strike
Where your finger lands also colours what it plays. A strum or a pluck placed toward one edge of the pad speaks brighter; placed toward the other, plainer - and a finger resting on a string keeps holding its colour there, the way a bow held on a string keeps its voice. The brightness rides the same wire as everything else the instrument expresses - see MIDI and MPE.
Together the two halves make the touchpad a second instrument after the strum: strike with one motion, then stay on the glass and play the ringing chord with the other.