The beautiful Apple AirPods Max headphones definitely need a travel case for better protection.
Here are what Geekria customized made for this headphones.
UltraShell Case for Travel with Smart Case
SoftShell Pouch for Travel with Smart Case
UltraShell Case Integrated with Sleep Mode Control
When put headphones in the case, they go into the sleep mode / low power mode immediately to preserve battery charge, same effect as you put them into the original smart case.