MinMax property drawer for Unity - Add a [MinMax] attribute to a property to draw a useful min/max setting slider.

MinMaxAttribute.cs

// NOTE DONT put in an editor folder

using UnityEngine;

public class MinMaxAttribute : PropertyAttribute
{
    public float MinLimit = 0;
    public float MaxLimit = 1;

    public MinMaxAttribute(int min, int max)
    {
        MinLimit = min;
        MaxLimit = max;
    }
}

MinMaxDrawer.cs

// NOTE put in a Editor folder

using UnityEngine;
using UnityEditor;

[CustomPropertyDrawer(typeof(MinMaxAttribute))]
public class MinMaxDrawer : PropertyDrawer
{
    public override void OnGUI(Rect position, SerializedProperty property, GUIContent label)
    {
        MinMaxAttribute minMax = attribute as MinMaxAttribute;

        if (property.propertyType == SerializedPropertyType.Vector2)
        {
            float minValue = property.vector2Value.x;
            float maxValue = property.vector2Value.y;
            float minLimit = 0;
            float maxLimit = 1;

            EditorGUI.MinMaxSlider(position, label, ref minValue, ref maxValue, minLimit, maxLimit);

            var vec = Vector2.zero; 
            vec.x = minValue;
            vec.y = maxValue;

            property.vector2Value = vec;
        }

        
    }
}

VolumeRandomizer.cs

// This componnet Demos how to use MinMax attribute! Uses the ReadOnly attribute found here https://gist.github.com/LotteMakesStuff/c0a3b404524be57574ffa5f8270268ea

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

[ExecuteInEditMode]
public class VolumeRandomizer : MonoBehaviour {

    public AudioSource source;
    public float Size;
    [MinMax(0,1)]
    public Vector2 VolumeRange = new Vector2(0, 1);
    [ReadOnly]
    public Vector2 RawMinMaxVolumes;
    [ReadOnly]
    public float valueRange;

	// Use this for initialization
	void Start () {
	}
	
	// Update is called once per frame
    [ExecuteInEditMode]
	void Update () {
        valueRange = VolumeRange.y - VolumeRange.x;
        RawMinMaxVolumes = VolumeRange;
    }
}