Actually, it was always our thought that the recorders were made of
an extremely ultralight material -- there's an actual term for this sort
of thing that has just fallen out of my head -- kept in place by a fan
system operating at high speed, gyroscopically controlled to remain
stable.

Sort of small hovercraft technology up 200 years or so. Ain't much
magic or, for that matter, much high-tech involved in it.

jms