Trying to move a instantiate gameobject with mousedown

I've been trying for a while to create a gameobject from a prefab with a GUI button and while holding down the button move it to its location then release the button and have the object placed there.

I do not want to use any raycast since there is no plane in the game.

So far i can get the object to spawn where i push the button but not move.

Any help on this would be greatly appreciated.

 public void OnGUI()
 {
 bool Item Drag
 if(GUI.Button (DRButton1, Door))
             {
                 GameObject Box = (GameObject)Instantiate(Model_Box, Camera.main.ScreenToWorldPoint(Input.mousePosition), Quaternion.Euler(0,0,0));
                 Box.name =  "Box";
                 ItemDrag = true                
             }
 
 if(ItemDrag)
         {
             
             
             if(Input.GetMouseButtonDown(0))
             {    
             
             
                 Box.transform.Translate(Camera.main.ScreenToWorldPoint(Input.mousePosition));
             }
         }
 }