Extrusion {
  eventIn MFVec2f    set_crossSection
  eventIn MFRotation set_orientation
  eventIn MFVec2f    set_scale
  eventIn MFVec3f    set_spine
  field   SFBool     beginCap         TRUE
  field   SFBool     ccw              TRUE
  field   SFBool     convex           TRUE
  field   SFFloat    creaseAngle      0
  field   MFVec2f    crossSection     [ 1 1, 1 -1, -1 -1, -1 1, 1 1 ]
  field   SFBool     endCap           TRUE
  field   MFRotation orientation      0 0 1 0
  field   MFVec2f    scale            1 1
  field   SFBool     solid            TRUE
  field   MFVec3f    spine            [ 0 0 0, 0 1 0 ]
}

• Very much more efficient than equivalent indexedFaceSet
• To create torus, use circle cross-section, repeat first and last point of spine, set caps to FALSE
• Can animate spine using set_spine event
• Can animate cross-section, scale and orientation fields similarly
• Very, very powerful node, use as much as possible

Example