diff --git a/src/main.rs b/src/main.rs
index 73e125f..4c9838b 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -9,7 +9,6 @@ use render::{World,Camera};
 use vec3::{Point3,Vec3};
 
 use material::{Metal,Lambertian,Material};
-use std::sync::Arc;
 
 
 fn main() {
@@ -19,16 +18,16 @@ fn main() {
     let viewport_height = 2.0;
 
     let m = Lambertian::new(Vec3::new(0.5,0.5,0.5));
-    let world_m: Arc <dyn Material> = Arc::new(m);
+    let world_m: Box <dyn Material> = Box::new(m);
 
     let m = Lambertian::new(Vec3::new(0.1, 0.2, 0.5));
-    let center_m: Arc <dyn Material> = Arc::new(m);
+    let center_m: Box <dyn Material> = Box::new(m);
 
     let m = Metal::new(Vec3::new(0.8, 0.8, 0.8), 0.3);
-    let left_m: Arc <dyn Material> = Arc::new(m);
+    let left_m: Box <dyn Material> = Box::new(m);
 
     let m = Metal::new(Vec3::new(0.8, 0.6, 0.2), 0.5);
-    let right_m: Arc <dyn Material> = Arc::new(m);
+    let right_m: Box <dyn Material> = Box::new(m);
 
     let mut camera = Camera::new(aspect_ratio,image_width,focal_length,Point3::new(-1.0,1.0,1.0),Point3::new(0.0,0.0,-1.0),90.0);
     let mut world = World::new();
diff --git a/src/object.rs b/src/object.rs
index 3eea3ff..5ebe938 100644
--- a/src/object.rs
+++ b/src/object.rs
@@ -2,22 +2,21 @@ use crate::vec3::{Point3, Ray, Vec3, Interval};
 use crate::material::{Material,Scatter};
 
 use rand::prelude::*;
-use std::sync::Arc;
 
 
 pub trait Hittable: Send + Sync{
-    fn hit(&self, ray: Ray, interval:Interval) -> Option<HitRecord>;
+    fn hit(&self, ray: Ray, interval:Interval) -> Option<HitRecord<'_>>;
 }
 
-pub struct HitRecord {
+pub struct HitRecord<'a> {
     point: Point3,
     normal: Vec3,
     root: f64,
     front_face: bool,
-    material: Arc<dyn Material>,
+    material: &'a dyn Material,
 }
 
-impl HitRecord {
+impl HitRecord <'_> {
     pub fn normal(&self) -> Vec3 {
         self.normal
     }
@@ -44,17 +43,17 @@ impl HitRecord {
 pub struct Sphere {
     radius: f64,
     center: Point3,
-    material: Arc<dyn Material>
+    material: Box<dyn Material>
 }
 
 impl Sphere {
-    pub fn new(radius: f64, center: Point3, material: Arc<dyn Material>) -> Self {
+    pub fn new(radius: f64, center: Point3, material: Box<dyn Material>) -> Self {
         Sphere { radius, center , material}
     }
 }
 
 impl Hittable for Sphere {
-    fn hit(&self, ray: Ray, interval:Interval) -> Option<HitRecord> {
+    fn hit(&self, ray: Ray, interval:Interval) -> Option<HitRecord<'_>> {
         let oc = self.center - ray.origin();
         let a = ray.direction().length_squared();
         let h = Vec3::dot(ray.direction(), oc.to_vec());
@@ -80,7 +79,7 @@ impl Hittable for Sphere {
             point,
             normal,
             front_face: false,
-	    material: self.material.clone()
+	    material: self.material.as_ref(),
         };
         tmp.set_face_normal(ray, normal);
         Some(tmp)
diff --git a/src/render.rs b/src/render.rs
index f4477e5..142fcf4 100644
--- a/src/render.rs
+++ b/src/render.rs
@@ -21,7 +21,7 @@ impl World {
 	self.objects.push(Arc::new(object));
     }
 
-    pub fn hit(&self, ray: Ray, interval:Interval) -> Option<HitRecord> {
+    pub fn hit(&self, ray: Ray, interval:Interval) -> Option<HitRecord<'_>> {
 	let mut hit_anything = None;
 	let mut closest_so_far = interval.max();