Mintyswitch1
Mindtrip writes –

The Problem:
I recently installed a StarCom system for an upcoming tour of the Oregon/Washington coast. My girlfriend tours with me, and thus far we’ve used our own iPods with in-ear monitors for entertainment, and hand signals for communication. On this tour a buddy is coming along who wanted bike-to-bike communications; thus the StarCom. My girlfriend wanted to be able to listen to the radio conversations, as well as talk to me, but I realized that if I didn’t do something, she was going to wind up running the iPod. We have different musical tastes, and while we both listen to audiobooks we’re usually into different books at any given time. This meant I was going to have to listen to her stuff the whole time. Unacceptable!!!

The Solution:
We use in-ear monitors, so I got the StarCom headsets that allow the use of your own headphones. I quickly realized this would make it possible to rig up some kind of switch or patch cable system that would allow her to listen to her own iPod if she didn’t want to listen to whatever I had running on mine, but switch over to the intercom if I needed to talk to her. I scoured the internet looking for solutions, as well as all my local electronics stores, to no avail. No one makes a switchable audio input for personal headset use. However, I DID find a switch at RadioShack that lets you switch between computer audio input and an auxilliary audio, as well as switching output between computer speakers and headsets (clicky. And for only $2!! I figured if it were small enough, she could stick this in her pocket and switch between the intercom and her iPod at will.

Switchable audio homebrew solution – Link.

All in an Altoids tin of course!