"If y'all find something that works for the guitar, would you be kind enough to let me know? I need something similar for the baby grand. Possibly I could adapt it to fit. Thanks." Peace

I'm always surprised that so many people never think of the obvious solution. If you take out the air and collapse the instrument you can transport just about anything.

It doesn't work with books, of course. That's because the air has already been taken out.