Chip- Yeah, I saw one years ago, in Denver. Solid Oscar Schmidt, no soundhole. And painted bright YELLOW. It was called the "electric banana", as I recall. I never played it, but it sounded pretty good, though not as good as the better quality acoustic harps in our group. I've never seen one since.

Regarding pickups, (if I might be allowed a personal plug), I use a Pick-Up the World model #30 on my old beater OS. Same pick-up I have on my Guild six string. It's about three inches long, but manages to pick up the entire soundboard quite well. I was surprised. I put it on the soundboard beneath the chord mechanism, so as to be out of sight, and filed a little notch in the upright chord bar support for the wire. The pickup unit itself is flexible and attaches with self-adhesive tape, so mounting is easy.

As far as building a solid body autoharp, utilizing piezos: The various piezo "dots" available are not up to the job, IMO. You might be able to spread them out enogh to cover the entire soundboard, but the wiring would be tricky, to say the least. So far it hasn't been tried using Pick-Up the World, and I'm quite skeptical. PUTW would work better than the other sensors available, I'm certain. Rick Rubarth, a builder of fine concert and folk harps in Boulder, CO, devised a line of solid body concert harps utilizing PUTW. The sound is great, and the overall cost to his customers is less.

But the autoharp is a different animal. So far, PUTW has been used with great success on solid body instruments such as bass and electric guitar. The proper mounting for the film is in the bridge of these instruments, using a thin metal shim to prevent rupture of the film.

The "bridge" of an autoharp, however, is at the heel of the instrument, far from being tonally ideal. Hence my skepticism. I do know that Pick Up the World pick-ups work very well on acoustic autoharp soundboards. So, while theoretically possible, I think the idea of using piezo pick-ups for a solid body autoharp is impractical.
I don't see any advantages to such an approach. True, a solid body autoharp would be easier and less expensive to make, but I don't think the sound would compare with a good quality hollow body harp, with a good pick-up such as PUTW. Also, wouldn't a solid body autoharp weigh like twice as much as a hollow body? Thanks, BlueJay