While we don't yet have a dedicated case for the Dave Smith Tempest, one of the cases in our UNISON may be a good fit!
The dimensions we have on hand for the Dave Smith Tempest are: (15.4 x 9 x 2.5) inches. If that aligns with what you have, we would recommend looking at the UNISON Case for the Korg Monologue: (16 x 11.5 x 3) inches.