While we do not currently have any case options for the Maxwell or MM-100, users have found this case to work well:
Geekria Shield Case (on Amazon)
Please note we do not officially endorse this product, so your mileage may vary. Other options may exist online.
In case you'd like to find a different option, the dimensions of the ear cups are about 100mm, and the headphones are about 200mm tall. Please note that Audeze headphone models with similar chassis designs are not designed to be set flat, so any case option will have to take that into account.