Custom Editor Vector3Field not working

Hello!

This is the first time I am trying to build a custom inspector and honestly I am overwhelmed by the many classes and definitions.
EditorGUI, EditorGUILayout, EditorWindow…
I followed a few different tutorials, e.g. this one but I can’t get it to work.

I am trying to display two Vector3 fields from a certain class as Vector3Fields like in the default transform inspector. So not exactly complicated (I thought…).

Here is my class:

using UnityEngine;
using System.Collections;

	[System.Serializable]
	public class VectorAndMod : MonoBehaviour {
		
		public Vector3 vector;
		public Vector3 mod;
	
	
	}

And here is my Editor class:

using UnityEngine;
using UnityEditor;
using System.Collections;

[CustomEditor(typeof(VectorAndMod))]
class VectorAndModEditor : Editor {
	
	public override void OnInspectorGUI () {
		
		VectorAndMod vectorAndMod = (VectorAndMod) target;
        vectorAndMod.vector = EditorGUILayout.Vector3Field ("Vector", vectorAndMod.vector);
        vectorAndMod.mod = EditorGUILayout.Vector3Field ("Mod", vectorAndMod.mod);
		
        if (GUI.changed)
            EditorUtility.SetDirty (vectorAndMod);
		
    }
	
		
}

What am I missing?
Thanks in advance!!!

Look at PropertyDrawers