Gap Shuffle

shortcut yg in edit curve mode, and depending on your menu keymap

The Gap Shuffle tool is used to move the gap between a spline's two end points to a different position within the spline, without changing any of the spline point's locations.
By default the tool will make a spline cyclic, if it isn't already.

Gap Shuffling is especially useful when using Blendulate with cyclic splines, but may have other use cases too.
If there are existing radii/arcs/blends on the active spline, the tool will attempt to find the outlier segments - based on their length - and will prioritize them, when cycling through and previewing the new gap location.

Selection

• an active POLY spline

Statusbar

The statusbar at the bottom of Blender - after invoking the tool - provides all the info you need in regards to what keys you can press to modify the tool's behavior.

Using Gap Shuffle

here's a cyclic spline with its gap at the bottom

• Scrolling with the mouse wheel or using the 1 and 2 keys, the gap location within the spline can be changed
  • the original gap is drawn in yellow, and can not be selected
  • the new gap is previewed by a black line and two highlighted points
  • With two or more outlier segments present, they will be highlighted, and only they will be shuffled through
• With two or more outlier segments present, outlier shuffling can be toggled with the Q key
  • Without outlier segments present or with outlier shuffling disabled, any other segment, except the original gap, can be chosen as the new gap location
• Spline cyclicity can be toggled using the C key

with gap re-positioned, the bottom corners can be blendulated too

and even though it makes no difference, you can bring the gap back to where it was initially

Tilt Preservation

As of version 1.5, when the curve or individual points are tilted, Gap Shuffle visually preserves the bevel/profile orientation by compensating tilt for the new gap start.
Previously moving the cyclic gap used to twist the visible profile even when the per-point tilt values were stored and maintained correctly.
Reverse does the same for direction flips - together they keep tilted bevels and profiles looking right after either operation.

Gap Shuffle and Reverse now visually preserve (flip or compensate) tilt