diff --git a/installer/installer.nix b/installer/installer.nix
new file mode 100644
index 0000000..5488783
--- /dev/null
+++ b/installer/installer.nix
@@ -0,0 +1,26 @@
+{ pkgs, config, lib, ... }:
+{
+  config = {
+  systemd.services.custom-install = {
+    description = "Custom installation script";
+    wantedBy = [ "multi-user.target" ];
+    after = [ "network.target" ];
+    path = [ pkgs.util-linux pkgs.parted pkgs.nixos-install-tools pkgs.nixos-anywhere pkgs.diskco ];
+    
+    serviceConfig = {
+      Type = "oneshot";
+      RemainAfterExit = true;
+    };
+
+    script = ''
+      # Your installation commands here
+      if [ ! -f /etc/installation-completed ]; then
+        # Run your installation steps
+        
+        # Mark as completed
+        touch /etc/installation-completed
+      fi
+    '';
+  };
+  };
+}
\ No newline at end of file
diff --git a/size-test/base.nix b/size-test/base.nix
index 975742a..c06f10e 100644
--- a/size-test/base.nix
+++ b/size-test/base.nix
@@ -1,7 +1,10 @@
 { config, pkgs, lib, ... }:
 
 {
-  imports = [ ../quickly.nix ];
+  imports = [ 
+    ../quickly.nix
+    ../installer/installer.nix
+    ];
  config = {
    users.users.nixos = {
      isNormalUser = true;