Thermoforming machine - GIF

[IAMSatisfied]

It appears that he brings the pliable dome up to the indicator, but when he removes it from the clamp, the finished dome is significantly below the indicator... I wonder if he intentionally allow it to shrink doen once air pressure ceases to be applied?

I visited a plastic forming shop in Denver that makes skylight by this method, except they use a laser beam as an automatic height limit... when the beam is broken by the dome, the air flow is cut off, and when it shrinks down, air flow is re-established to maintain the specific height.