Umm....wanted the sound of a marching snare drum approaching and departing in a stereo field. Could've achieved a left-to-right motion by simply panning the sound, but good listeners would know that was how it was done, because there would be no timbral change. So, we attached a headphone amp to the back of a real field-mounted snare drum:
Then, I played the drum (which had been loaned by a colleague) while moving it, recording it with a pair of ribbon microphones in an 'X-Y' pattern:
Then, because this sound we got was a bit pointed, we sent the recorded signal through a speaker mounted on top of another snare and recorded the resultant sympathetic 'buzz' of the snares with a reference microphone:
It was surprisingly easy to get the actual effect I wanted, perhaps 70 minutes of work, but this was for just eight bars of audio. The result was a bit spooky, though, so well worth the effort. By the way, this is the same track that I hired Blake Jones to play theremin on and to which we added sirens (as in background-singing bombshells) which morph into 'sirens' (as in bomb shelters, seek cover).