I love old component packages and lead frames. I can imagine a ceramic substrate hybrid circuit being mounted in this carrier and hermetically sealed for some rough and tumble 1960s era aerospace application. While these things are obsolete in today's SMT world, it would be neat to package some small microcontroller in there for a one-off novelty show piece. A sort of useful art piece combining the old world electronics technology with the contemporary one. It's really nice and you better keep it around since you don't find this stuff any longer.