While we don't yet have a dedicated case for the Novation Launchkey 49, one of the cases in our SUSTAIN line may be a good fit!
The dimensions we have on hand for the Novation Launchkey 49 are: (30.5 x 10.6 x 3.5) inches. If that aligns with what you have, we would recommend looking at the SUSTAIN Case For Prophet Rev2, Prophet 6 or OB6: (35.1 x 13.7 x 4.7) inches.