Yamaha made 3 hard cases out of fiberglass for their synthesizers. These were designed to protect the DX1, DX5, and DX7 respectively. This set was 18 years on the making -Mission accomplished!
Mission complete
You peaked my curiosity
I first saw the Casio CK-500 in 1985. It’s still until now the only keyboard I know of with dual cassette players. Dubbing from tape to tape was quite a big deal in the mid 1980’s and I was very tempted to buy this novel machine. Unfortunately those mini keys were a little unprofessional so I gave it a miss. It’s still a rather cool toy to have, even for someone who cant play.
https://review.wolfarchitects.design/casio-ck-500-keyboard-1985/