Cache GetComponent correctly in C#

Here is my problem. Button on wall has button script. Elevator platform has Elevator script (everything is C#) When Button is pushed it needs to call GoToFloor in the Elevator script.

I cobbled together this from other examples on Unity Answers.

How do I make the result of GetComponent Public so every function in Button.cs can use it? Currently it is resisting my attempts to use GetComponent in one place and save it for use somewhere else without calling GetComponent AGAIN (which I have read you only want to do once for efficiency sake:

CODE:

Elevator.cs using UnityEngine; using System.Collections; using UnityEngine; using System.Collections;

public class Elevator : MonoBehaviour {

 public Transform target;
 private float initialx = 159 ;
 private float initialy = 0.2F ;
 private float initialz = 821.4F;
 private float floor1Height = 0F;
 private float floor2Height = 10F;
 private int floorNum;
 private float elevatorSpeed ;
 private Vector3 velocity = Vector3.zero;
 private float smoothTime = 0.3F;
 private float floor3Height ;
 private GameObject elevator;
 private bool elevatorActive = false;
 private float elevatorDestination ;

 void Start()
 {
     // initialise variables which must have a value, otherwise errors ensue
     elevator = this.gameObject;
     elevatorActive = false;
     elevatorDestination = elevator.transform.position.y;
 
 }

 void Update() {
     if(elevatorActive)
     {
         MoveElevator();
     }
 }

 void MoveElevator()
 {
     // Move the elevator

     Vector3 targetPosition = target.TransformPoint(new Vector3(initialx,initialy + elevatorDestination,initialz));
     transform.position = Vector3.SmoothDamp(transform.position, targetPosition, ref velocity, smoothTime);
            
     
     //elevator.transform.position.y = Mathf.Lerp(elevator.transform.position.y, elevatorDestination, elevatorSpeed * Time.deltaTime);

     // Disable the elevator if it is within a very small margin of the destination, ie it is 'close enough' so stop
     //if(Mathf.Abs(elevator.transform.position.y - elevatorDestination) < 0.01)
     //{
     //    print("stopped elevator");
     //    elevatorActive = false;
     //}
 }

 public void GoToFloor(int floorNum)
 {
     switch(floorNum)
     {
         case 1:
             elevatorDestination = floor1Height;
             break;
         case 2:
             elevatorDestination = floor2Height;
             break;
         case 3:
             elevatorDestination = floor3Height;
             break;
         default:
             elevatorDestination = floor1Height;
             break;
     }

     elevatorActive = true;
 }

 void StopElevator()
 {
     elevatorActive = false;
 }

 void ResumeElevator()
 {
     elevatorActive = true;
 }

}

BUTTON CODE:

 using UnityEngine;

using System.Collections;

public class Button : MonoBehaviour { public GameObject target; public bool pushed = false; //public myelevator; (does not work)

 void Start() {
     //GameObject myelevator = GameObject.Find("elevator");
      Elevator myelevator = GetComponent<Elevator>();  // How do I export myelevator so it can be used in OnMouseUp()?
     // Doing a GetComponent once is the best idea I understand, but how do I save it for other functions?
     
     //myelevator bar = myelevator.GetComponent<GoToFloor()>();
     
 }

 void OnMouseEnter() {
     //renderer.material.SetColor("_OutlineColor", Color.blue); .//not important right now
 }

 void OnMouseExit() {
     //renderer.material.SetColor("_OutlineColor", Color.black); //not important right now
 }

 void OnMouseUp() {
     pushed = true;
     //Elevator.elevator.GoToFloor(2);

     myelevator.GoToFloor(2); // myelevator from above not recognized! why?
     Debug.Log("Button Pushed.");
 }

   
 void Done() {
     pushed = false;
 }
 

}