A cousin of mine used to use a flexible necked condenser mini-mic designed for saxophones. Then he had an outfit designed with 2 of them which he fastened to the bridge piece and bent over each f-hole.

It sounded great, but once I saw him perform a concert while he had a cold. The mics picked up a perfect stereo image of the snot being sucked back into his nose with every inhalation of breath. Then he started using that sound as percussion (a sort of aural punctuation) that night. When life gives ya lemons...

He's not using those mics anymore.