Try some sort of bowing gesture. Think of piping the sound into a body and being able to move the pickups/mics around. Warping/bending a metal plate. Make the raw sounds of the impulse bleed out into the signal (on a slider). Play with the range of the position (make the range go lower and be weighted towards the lower end (x^2?)) stereo impulses (if impulses are mono, can use 2 different samples for left and right). Try different types of model - waveguide? wind?