SplineLength is a Modeler plugin that computes the total length of any splines you have selected. It properly accounts for ends being visible / invisible.

Motion to curve allows you to import .mot files into modeler.

Creates a spline in Modeler based on a motion path in Layout.

Have segment control in freezing curves. This script is similar to that of the standard Freeze Curves & Patches CS command in Modeler, but with couple of distinct differences. First, this script enables you to specify how much resulting points there would be in your final frozen geometry. Secondly, the script can turn the resulting [...]

Quickly insert splines within a spline cage. This script will connect a series of selected splines by creating intersecting splines. Just select two or more splines in a certain direction and run the script.

From the developer’s website using Google Translate: Extrude tool in real-time version of the curve transformation function. Curve per node, scale and rotation can be moved. In addition, between starting and ending points of the curve can be scaled rotation.

Create new polygons, like the native pen tool, with snapping. Can also create curves, quad strips and polychains.

Create bezier style curves. The curves can be interactively modifed using bezier handles. Instead of curve creation, the plugin can also use the bezier curve as a base for other geometry types Line: 2 point poly chains. Belt: Create polygon strips interactively following the curve for adjustments. Tube: Extrude a tube, or tubes along the [...]

From the developers website, using Google Translate: Changing the curvature of the curve FG layer and extended toward the end direction of the curve starting point to create the specified layer.

From the developers website, using Google Translate: You can add points to the end of the curve, or the separate end points.