Guardian makes a lightweight hard case. It wouldn't fit in my trunk.

I use the Kaces 9kb case. For added protection, I put a stretch nylon keyboard cover over the keyboard when it is in the case, and on top of that I put a section of a foam mattress pad.

There's a smaller Kaces that might be a tighter fit. I pack a tupperware container next to my kb with a/c adapter, mic cable, and headset mic.

Beakybird