Pilot 16,
Sorry, but if your project needs to be completely original the carb ice detector is out. I flew a PA-28 with one a few weeks ago.
However this one was notoriously unreliable so maybe a reliable carb ice detector?
How about some sort of audio visual training aid? A few of cheap digital cameras to show external and internal views, an audio feed to record the R/T, if possible a digital recording of some instrument info - e.g. GPS track?. All recorded in a form suitable for re-running on the gound during debrief - e.g. a series of windows displaying the synchronised information?
Good luck with whatever you come up with,
AliB