If your horizontal excitation can be cast as a force, then you could hack it into gravity. it’s not a frame indifferent equivalent of actually moving the container, but it’s the most straightforward if you can live with it. other options are to model the container with particles and force the motion of the “container particles”, Otis Walton has done this for a tumbler setup somewhat recently (@benyahia might have his udf? I can’t seem to find it in my email) . Finally, it’s possible to move the STL, but it’s difficult and expensive and as far as I know only @jeff.Dietiker knows how to do this.