Simple Piston

The fastest and simplest way to make a piston. It requires a selection of two objects, with one active. Their origins are used to define the pivot points. The operator works regardless of orientation and if needed, it can align the armature/rig to the objects used to create it.

Note:

When the align to active option is used, the use axis setting is rather important and when wrongly set, the piston may disappear until you set the right one. The y axis should point towards the B empty. In addition, both UI elements that appear briefly should have the same orientation.