How can i make a GUI for my battery life?

Ive made this script where i have a flashlight with battery life, and the lower it gets the lower the intensity gets so it gets weaker and weaker. Do you have any good idea on how to make a GUI texture in the corner, like a bar that follows and gets lower as the batterylife drain?

Dont really know if this is necessary but heres some code for ya:

 #pragma strict
  
 //Variables START
  
 //Light Source && Battery Life
 var flashlightLightSource : Light;
 var lightOn : boolean = false;
 var lightDrain : float = 0.01;
 var batteryLife : float = 0.0;
 var maxBatteryLife : float = 2.0;
  
 //Variables END
  
 function Start()
 {
         batteryLife = maxBatteryLife;
         flashlightLightSource = GetComponent(Light);
 }
  
 function Update()
 {
         if(lightOn && batteryLife >= 0)
         {
                 batteryLife -= Time.deltaTime * lightDrain;
         }
        
         flashlightLightSource.light.intensity = batteryLife;
        
         if(batteryLife <= 0)
         {
                 batteryLife = 0;
                 lightOn = false;
         }
        
         if(Input.GetKeyDown("n"))
         {
                 toggleFlashlight();
                    
                
                 if(lightOn)
                 {
                         lightOn = false;
                 }
                 else if(!lightOn && batteryLife >= 0)
                 {
                         lightOn = true;
                 }
         }
 }
  
 function toggleFlashlight()
 {
         if(lightOn)
         {
                 flashlightLightSource.enabled = false;
         }
         else
         {
                 flashlightLightSource.enabled = true;
         }
 }