Instantiate and Scale with Mouse Click.

Hey @BiffJenkins, I would use Input.mousePosition and Camera.ScreenPointToRay(). Try this script I just wrote and drop it on one of your Cameras:

     [SerializeField] GameObject prefab;
     [SerializeField] [Range(1f, 200f)] float drawDistance = 50f;
 
     GameObject drawObject;
     bool drawing = false;
     Vector3 mouseStartingPosition;
 
     Camera cam;
 
     void Start(){
         // load our camera
         cam = GetComponent<Camera> ();
     }
     
     // Update is called once per frame
     void Update () {
         // check if we want to start, end, or continue drawing
         if (Input.GetMouseButtonDown (0)) {
             startDraw ();
         } else if (Input.GetMouseButtonUp (0)) {
             endDraw ();
         } else if (drawing) {
             whileDrawing ();
         }
     }
 
     void startDraw(){
         // create a new instance
         drawObject = Instantiate (prefab, Vector3.zero, Quaternion.identity) as GameObject;
 
         // save our draw starting point
         mouseStartingPosition = Input.mousePosition;
 
         // put the new instance where we pointed to with a set distance (or collision)
         Ray ray = cam.ScreenPointToRay(mouseStartingPosition);
         drawObject.transform.position = transform.position + ray.GetPoint (drawDistance);
 
         // allow the Update to call whileDrawing()
         drawing = true;
     }
 
     void endDraw(){
         // forbid the Update do call whileDrawing()
         drawing = false;
     }
 
     void whileDrawing(){
         // manipulate the instance in whatever way you like
         float mouseDistance = Vector3.Distance (mouseStartingPosition, Input.mousePosition);
         drawObject.transform.localScale = new Vector3 (1f, mouseDistance, 1f);
     }