The application will written appdata\programs, PhysicalFile is now a struct. should be enough

Creator/PhysicalFile.cs

@@ -1,6 +1,6 @@
 namespace KattekerCreator
 {
-    public class PhysicalFile
+    public struct PhysicalFile
     {
         public PhysicalFile(string source, string target)
         {
@@ -8,7 +8,7 @@
             Target = target;
         }
 
-        public string Source { get; }
-        public string Target { get; }
+        public readonly string Source;
+        public readonly string Target;
     }
 }