Weapon customization Help needed

so i have been working on an fps game and i resently made a weapon customization script, you can customize the weapons like your supposed too but i dont know how to get them to load into the game itself someone pls help

 using UnityEngine;
 using System.Collections;
 
 public class Weapon : MonoBehaviour 
 {
     public string CurrentMenu;
 
     public GameObject G36_WEAPON;
 
         public GameObject Holo_Sight;
 
         public GameObject ACOG;
 
         public GameObject Silencer;
 
     void Start () 
     {
         CurrentMenu = "Hub";
         Holo_Sight.SetActive (false);
         ACOG.SetActive (false);
         Silencer.SetActive (false);
         G36_WEAPON.SetActive (false);
 
 void Update () {
 
     }
 
     public void NavigateTo(string nextmenu)
     {
         CurrentMenu = nextmenu;
     }
 
     void OnGUI()
     {
         if (CurrentMenu == "Primary")
             Primary ();
         if (CurrentMenu == "Hub")
             Hub ();
         if (CurrentMenu == "G36")
             G36 ();
         if (CurrentMenu == "G36_Optics")
             G36_OP ();
         if (CurrentMenu == "G36_Barrel")
             G36_Barrel ();
 
 public void Hub()
     {
         if (GUI.Button (new Rect (10, 10, 200, 50), "Primary")) 
         {
             NavigateTo ("Primary");
         }
     }
 
     private void Primary()
     {
         if (GUI.Button (new Rect (10, 10, 200, 50), "Back")) 
         {
             NavigateTo("Hub");
         }
         if (GUI.Button (new Rect (10, 70, 200, 50),                               "G36")) 
         {
             NavigateTo ("G36");
         }
 
 private void G36()
     {
         G36_WEAPON.SetActive (true);
         FAMAS_WEAPON.SetActive (false);
         AUG_WEAPON.SetActive (false);
         M16_WEAPON.SetActive (false);
         if (GUI.Button (new Rect (10, 10, 200, 50), "Back")) 
         {
             NavigateTo("Primary");
         }
         if (GUI.Button (new Rect (10, 70, 200, 50), "Optics")) 
         {
             NavigateTo("G36_Optics");
         }
         if (GUI.Button (new Rect (10, 130, 200, 50), "Barrel")) 
         {
             NavigateTo("G36_Barrel");
         }
     }
     private void G36_OP()
     {
         if (GUI.Button (new Rect (10, 10, 200, 50), "Back")) 
         {
             NavigateTo("G36");
         }
         if (GUI.Button (new Rect (10, 70, 200, 50), "None")) 
         {
             Holo_Sight.SetActive (false);
             ACOG.SetActive(false);
         }
         if (GUI.Button (new Rect (10, 130, 200, 50), "Holo_Sight")) 
         {
             Holo_Sight.SetActive (true);
             ACOG.SetActive(false);
         }
         if (GUI.Button (new Rect (10, 190, 200, 50), "ACOG")) 
         {
             Holo_Sight.SetActive (false);
             ACOG.SetActive(true);
         }
     }
     private void G36_Barrel()
     {
         if (GUI.Button (new Rect (10, 10, 200, 50), "Back")) 
         {
             NavigateTo("G36");
         }
         if (GUI.Button (new Rect (10, 70, 200, 50), "None")) 
         {
             Silencer.SetActive (false);
         }
         if (GUI.Button (new Rect (10, 130, 200, 50), "Silencer")) 
         {
             Silencer.SetActive (true);
         }