I remember seeing Steeleye Span* for the first time and watching the violinist with what I eventually dubbed a 'demon fiddle' -- I *believe* it was a clear plastic outline of a fiddle with red light (probably a red LED) in it, holding the bridge and the neck, and that's it.

*I am pretty sure it was Steeleye Span - whatever group shared Davey Pegg with Jethro Tull for a few years.