Thanks, I think I thought of that from 5th element or some other movie where they were building up a person, bone first, then tissue, then skin. The trick was doing it with just two scenes vs. something more complex. That is when I realized I can adjust the heights of the lower and upper section cut for each group as a timeline to control the start and finish of the build. As long as what you want is linear (e.g. no speed ramp up or down) you can get any timing you want with just two scenes.

@plot-paris said:

very impressive, David.

it never occured to me to use several section planes to show different elements of one building grow.

thanks for the demo file