Adding variables to a class at runtime

Hey guys, i'am making block editor for my game, the script is working in edit mode. I'am having a problem with adding variables for block creators when i choose a block type.

For example, when i choose "Gun" option the script should add new variables to class like "ShootingSpeed", and later the editor script should show it in the inspector. The problem lies in adding these variables, it seems that i'cant modify classes dynamicly or just add a new variables to class at runtime in C#.

 [ExecuteInEditMode]
 public class BlockCreator : MonoBehaviour
 {
 
     public enum Type // <---- This is a type enum, used for defining the type of the block and extending it's functionality
     {
         Hull,
         Gun,
         Engine,
         Utility,
             
     };
 
 
     public enum Collidable
     {
         Yes,
         No,
     };
         
     public int BX; //Volume variables
     public int BY;//Volume variables
     public float mass;
     public int HP;//Hit points
     public int Armor;
     public Type BlockType;
     public Collidable IsBlockCollidable;
     
     void Update()
     {
     
         if (BlockType = Type.Gun) {
                 // Add Variables or do other things to add variables 
         }
 
     }
     
 
     public void CreateBlock()
     {
     //TODO generate a new prefab made with variables from BlockCreator Class
     }
 }


 

And the BlockCreatorEditor

 [CustomEditor(typeof(BlockCreator))]
     public class BlockCreatorEditor : Editor
     {
 
          public override void OnInspectorGUI ()
         {
             DrawDefaultInspector ();
 
             BlockCreator myBlockCreator = (BlockCreator)target;
             
         if(GUILayout.Button("Create Block"))
             {
             myBlockCreator.CreateBlock();
             }
 
         }
     
     }
 

So in the end: Is there any way to add dynamicly variables at run time, and possibly how to do it? It would be the best to make it in C# but JavaScript can be used too.