Upper surface of yellow workpiece is kept always horizontal when placing it on four violet pins although its lower face consists of four planes.
Violet píns are identical.
Key factor: lower surfaces of the workpiece must be made parallel to its upper surface.
This design is used as an equalizer.
This video was made based on the design numbered as 937 in the book “Mechanical Fixtures Tooling” (with some changes because the simulation showed that the original is not workable).
It is used as an equalizer.