French hobbyist Sylvain came up with a fascinating project using 8 Magic Eye tubes from old equipment to make an audio spectrum analyzer. I’ve worked with magic eye tubes quite a few times, they’re very fascinating. Originally precursors to CRTs, they’ve found a lot of use as level indicators in all kinds of equipment up through about the late 1960s.
He built a beautiful project case for them, too. Click through to his blog to see the build log and all photos!