Known issues:

-The pole grows in both sides, so it becomes quite difficult to handle if it's long enough

-Due to hand sliding, you can end up with your hand outside of the pole itself when shrinking it.

-Even though the handle is there, for some fucking reason you can't access it if you're far enough from the center of the pole.


Here's the code.   

  public class ItemPowerPole : MonoBehaviour
    {
        protected Item item;
        private Transform poleTransform;


        private Transform meshTransform;
        private Transform colliderTransform;

        private Transform tipTransform;
        private Transform bottomTransform;

        private Vector3 orientation;

        private float growthSpeed = 0.05f;
        private float shrinkMultiplier = 1f;

        private float minPoleLength = 0.2f;

        private float colliderGrowthStep;
        private float meshGrowthStep;

        private bool isGrowing = false;
        private bool isShrinking = false;
        private bool trigger = false;
        private bool button = false;
        public bool scaleable = true;

        protected void Awake()
        {

            item = this.GetComponent<Item>();
            poleTransform = item.transform;
            meshTransform = poleTransform.Find("Mesh");


            colliderTransform = poleTransform.Find("Collider");

            colliderGrowthStep = colliderTransform.localScale.y * growthSpeed;
            meshGrowthStep = meshTransform.localScale.y * growthSpeed;



            tipTransform = item.definition.GetCustomReference("TipTransform");
            bottomTransform = item.definition.GetCustomReference("BottomTransform");

            item.OnUngrabEvent += OnPoleUngrabEvent;
            item.OnHeldActionEvent += OnPoleHeldAction;



        }

        void OnPoleHeldAction(Interactor interactor, Handle handle, Interactable.Action action)
        {

            if (action == Interactable.Action.UseStart)
            {
                    trigger = true;

                if (trigger && button)
                {
                    Freeze();
                }
                else
                {
                    isGrowing = true;
                }


            }
            if (action == Interactable.Action.AlternateUseStart)
            {
                button = true;
                if (trigger && button)
                {
                    Freeze();
                }
                else
                {
                    isShrinking = true;
                }

            }




            if (action == Interactable.Action.UseStop)
            {
                isGrowing = false;
                trigger = false;
            }

            if (action == Interactable.Action.AlternateUseStop)
            {
                isShrinking = false;
                button = false;

            }


        }

        
        void OnPoleUngrabEvent(Handle handle, Interactor interactor, bool throwing)
        {
            trigger = false;
            button = false;
        }

        void FixedUpdate()
        {
            if (isGrowing && scaleable)
            {
                Grow(1f);
            }

            if (isShrinking & scaleable)
            {
                Grow(-1*shrinkMultiplier);
            }


        }

        void Grow(float speed)
        {
            orientation = tipTransform.position - bottomTransform.position;
            orientation.Normalize();
            if (Vector3.Distance(tipTransform.position+orientation*speed*meshGrowthStep, bottomTransform.position-orientation* speed*meshGrowthStep) > minPoleLength)
            {
                meshTransform.localScale += new Vector3(0f, meshGrowthStep*speed, 0f);
                colliderTransform.localScale += new Vector3(0f, colliderGrowthStep*speed, 0f);
                tipTransform.position += orientation *meshGrowthStep* speed;
                bottomTransform.position -= orientation *meshGrowthStep* speed;
                item.handles[0].definition.axisLength = Vector3.Distance(tipTransform.position, bottomTransform.position);
                item.handles[0].data.highlighterShowAxisLine = true;
                item.handles[0].disableProximityHighlighter = false;
                item.handles[0].data.Refresh();
            }
        }

        void Freeze()
        {
            scaleable = !scaleable;
            item.rb.isKinematic = !item.rb.isKinematic;
            trigger = false;
            button = false;
        }
    }