From the Make: Flickr Pool:
V2 of my Tape Delay Machine uses two walkman type tape players. One is a Realistic Stereo Mate and the other is a Memorex XB.
Both players have a similar footprint, so I arranged them side by side and connected them together.
A single tape loop runs through two modified cassettes (each which have had one of their left or right sides removed).
The players themselves have had there walls (the two in the center, respectively) filed down, so the tape runs fluently.
The Realistic Stereo Mate has recording capability, where as the memorex does not.
This is purposeful, because the tape (which moves counter-clockwise) travels through the left player (Realistic) where it’s internal microphone records sound, and then travels to the Memorex which plays back the sound about 3 seconds later.