The icons to join and close vectors are located under the Edit Vectors section of the Drawing Tab.
This icon opens the Join Vectors Form
Open vectors are automatically identified and closed or joined to other vectors where the end points lie within the user definable tolerance.
Join with a Line finds the closest end points on 2 selected, open vectors and joins with a straight line. Close with a Line closes a single open vector with a straight line between its two end points.
Join with a Curve finds the closest end points on 2 selected, open vectors and joins them together with a smooth curve.
Cut2D Pro has two smooth joining methods:
Join Moving End Points finds the closest end points on 2 selected, open vectors, calculates the mid-point between them and moves the end points to this position.