Thank you everyone for the ideas. I think Bob's idea (listed below) is
one of the best. Once I realized that because of the curve of the case,
mounting a panel mount jack would result in having to place it in an
akward position, I started looking elsewhere. I still like the induction
idea, basically I'd be making two air/plastic core transformers. I'd be
a bit worried about the sound quality, plus I probably couldn't use my
original idea on how to affix anything external to the case -- magnets
:)

At the moment I'm focussing building a small FM transmitter into the
case. This will be a bit of work, as I'll need to fit in a bettery pack,
and some sort of externally triggerable power switch. However, there is
one huge benifit...when I am in a car, I can just transmit MP3s to the
car radio as well. In addition, it won't require any modification to the
case itself, so I can always remove it.

Anyway, I will keep you all posted on how it goes!

Josh
--
A common mistake that people make when trying to design something
completely foolproof is to underestimate the ingenuity of complete
fools.
        -Douglas Adams

Bob Ammerman wrote:
> How about three small brass bolts mounted thru the case with rubber washers.
> Now you build a strap/case/cradle that wraps around and makes contact with
> the three bolt heads.

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