While we don't manufacture or recommend a specific hard case for the StudioLive AR series mixers, you can always take the dimensions of the mixer to a case manufacturer (Gator, SKB, OSP, etc.) and they should be able to recommend a universal fit case from their product line that would accommodate the mixer.
In other words: while they may not make a "StudioLive AR16 Hard Case", they may be able to recommend another one of their cases that it would still fit inside of.