Creating Chalk-drawing Post Processing

I am new to C# and would like to create a chalk drawing post-processing effect. I want it to create a grain of chalk with the minimum radius *GrainMinSize* and the maximum radius *GrainMaxSize*, and the color of the grain will be a random pixel from the center of the grain within the distance *GrainSampleDistance*. If *ToleranceOn* is **true**, touching grains with a hue, saturation, and value within *SameColorTolerance* will be the same color. If *RefreshGrains* is **true**,the grains will redraw every *RefreshRate* seconds.

Can someone help me start out with this please?

This is my code so far.
**ChalkyModel.cs** using System; namespace UnityEngine.PostProcessing { [Serializable] public class ChalkyModel : PostProcessingModel { [Serializable] public struct Settings { [Tooltip("Minimum size of chalk grain in pixels")] public int GrainMinSize; [Tooltip("Maximum size of chalk grain in pixels")] public int GrainMaxSize; [Tooltip("Width & height of the area to get a random pixel for the grain")] public int GrainSampleDistance; [Tooltip("Turn on SameColorTolerance?")] public bool ToleranceOn [Tooltip("Tolerance for similarly colored grains to be the same color")] public float SameColorTolerance; [Tooltip("Redraw the grains every Refresh Rate seconds?")] public bool RefreshGrains [Tooltip("The rate in seconds the grains refresh.")] public float RefreshRate public static Settings DefaultSettings { get { return new Settings { GrainMinSize = 10, GrainMaxSize = 20, GrainSampleDistance = 15, ToleranceOn = false, SameColorTolerance = 2, }; } } } [SerializeField] Settings m_Settings = Settings.DefaultSettings; public Settings settings { get { return m_Settings; } set { m_Settings = value; } } public override void Reset() { m_Settings = Settings.DefaultSettings; } } } **ChalkyEditor.cs** using UnityEngine; using UnityEngine.PostProcessing; namespace UnityEditor.PostProcessing { using Settings = ChalkyModel.Settings; [PostProcessingModelEditor(typeof(ChalkyModel))] public class ChalkyModelEditor : PostProcessingModelEditor { struct ChalkySettings { public SerializedProperty GrainMinSize; public SerializedProperty GrainMaxSize; public SerializedProperty GrainSampleDistance; public SerializedProperty ToleranceOn; public SerializedProperty SameColorTolerance; public SerializedProperty RefreshGrains; public SerializedProperty RefreshRate; } ChalkySettings m_Chalky; public override void OnEnable() { m_Chalky = new ChalkySettings { GrainMinSize = FindSetting((Settings x) => x.GrainMinSize), GrainMaxSize = FindSetting((Settings x) => x.GrainMaxSize), GrainSampleDistance = FindSetting((Settings x) => x.GrainSampleDistance), ToleranceOn = FindSetting((Settings x) => x.ToleranceOn), SameColorTolerance = FindSetting((Settings x) => x.SameColorTolerance), RefreshGrains = FindSetting((Settings x) => x.RefreshGrains), RefreshRate = FindSetting((Settings x) => x.RefreshRate), }; } public override void OnInspectorGUI() { EditorGUILayout.PropertyField(m_Chalky.GrainMinSize); EditorGUILayout.PropertyField(m_Chalky.GrainMaxSize); EditorGUILayout.PropertyField(m_Chalky.GrainSampleDistance); EditorGUILayout.PropertyField(m_Chalky.ToleranceOn); EditorGUILayout.PropertyField(m_Chalky.SameColorTolerance); EditorGUILayout.PropertyField(m_Chalky.RefreshGrains); EditorGUILayout.PropertyField(m_Chalky.RefreshRate); } } }