Need Help! Scale an STL Mesh in only the Z axis?

I'm trying to find a way to scale a 3d STL mesh in the Z axis only, without changing the horizontal scale in X and Y, but I'm not seeing any help topics or finding any information through searches on this. I'd like to apply this to the model itself rather than a program tool path (not sure if that would mess with the offset in a non-uniform manner). I can do this by opening up the file in other applications first, but would prefer to be able to do it directly within Bobcad. :)
Thanks!