I don't think we've ever licensed anything, just used the free download from the Website. We've never used the Pro version, and I thought all the other versions were free. It was just SketchUp 2015, 2016, and then it went to "2017 Make" this year.

By the way, thanks again -I forgot to attach the file in the last message but here it is with the updated oscillating pistons. I think it'll work well as a template file to give to students to have them construct their own towers on top and try it at varying magnitudes. Like I mentioned before, it would be cool to actually get it working with simulated pieces that they'll actually use (straws, string, paper clips), but having a bunch of blocks to build with for conformity will probably have to do unless you guys have ideas. Earthquake Shake Table.skp