Hey Steve,
thanks for your kind answer. I put my real name into my signature as I saw that most forum members deal with that rule that way, hope that's ok...
The thing is, I want to produce 100 units of that thing so it shouldn't be some scavenged tape mechanism out of another machine. I built one of those units kind of successfully already and now I want it to be reproducable. I'm only looking for audio cassette tape mechanisms, 'normal' tape quality is completely ok for us. And yes, we're planning to use endless tapes inside there, I actually want to try to write digital codes at the beginning and ending of loops then as to be able to find the loops with a microcontroller.
Thanks for your thoughts on that.