Keyboardio Atreus travel case
The travel case perfectly cradles your keyboard, with a separate pocket for your USB cable.
While it's small enough to slide into your backpack, the case is sturdy enough to carry on its own. It has a handle made from nylon webbing and two D-rings you can use to attach your own shoulder strap. If instant access to your keyboard on the go is critical, you'll appreciate the case's fold-flat velcro belt loop.
(case only; keyboard and cable sold separately)