For an overview on creating, visualizing, and simulating mechanical constraints, including PlaneConstraint, see Mechanical Constraints. Also see Roblox Units to understand how Roblox units compare to metric units.
A PlaneConstraint moves its Attachment0 and Attachment1 into a position/orientation along a plane whose normal vector is the primary axis of Attachment0. Both parent assemblies remain free to translate and rotate unless otherwise constrained.
Compare the following examples for how the orientation of Attachment0 defines the plane, while the orientation of Attachment1 has no bearing.
