During WWI the allies used these devices to pacify their enemy.
Step 1: Download vintage recordings, and get a portable speaker system.
I found this speaker system at a dollar store, the speakers are just under two inches apart.
I wanted to play sounds from the first era of recordings. I downloaded a bunch of recordings from the cylinder preservation project, http://cylinders.library.ucsb.edu/index.php Songs from the right era add to the effect I wanted.
Your software and audio player will vary, and you'll know how to download music to your player.
Step 2: Foamy goodness.
I recommend you all run out and start scavenging parts. I'd love to see what the rest of you come up with.