diff --git a/option/option.lua b/option/option.lua
index 03b712b..9636c42 100644
--- a/option/option.lua
+++ b/option/option.lua
@@ -22,7 +22,7 @@ function Some(value)
     setmetatable(opt, {
         __index = Option,
         __tostring = function()
-            return "Some(" .. value .. ")"
+            return "Some(" .. value:__tostring() .. ")"
         end
     })
 
diff --git a/vector/vec3.lua b/vector/vec3.lua
index 0584fc7..577db41 100644
--- a/vector/vec3.lua
+++ b/vector/vec3.lua
@@ -1,30 +1,59 @@
+require "option.option"
+
 __Vec3 = {
-    x = 0,
-    y = 0,
-    z = 0
+    _x = 0,
+    _y = 0,
+    _z = 0,
 }
 
 function Vec3(vec)
     return setmetatable({
-        x = vec[1] or 0,
-        y = vec[2] or 0,
-        z = vec[3] or 0,
-    }, {__index = __Vec3,
-        })
+        _x = vec[1] or 0,
+        _y = vec[2] or 0,
+        _z = vec[3] or 0,
+    }, {
+        __index = __Vec3,
+        __tostring = __Vec3.__tostring,
+        __add = __Vec3.add,
+        __mul = __Vec3.scale,
+        __unm = function(self)
+            return __Vec3.scale(self, -1)
+        end,
+        __eq = function(self, other)
+            return
+                self._x == other._x
+                and self._y == other._y
+                and self._z == other._z
+        end,
+    })
 end
 
-function __Vec3:add(v1, v2)
-    return Vec3 { v1.x + v2.x, v1.y + v2.y, v1.z + v2.z }
+function __Vec3:add(other)
+    Vec3 { self._x + other._x, self._y + other._y, self._z + other._z }
+end
+
+function __Vec3:scale(factor)
+    return Vec3 { self._x * factor, self._y * factor, self._z * factor }
 end
 
 function __Vec3:length()
-   return math.sqrt(self.x ^ 2 + self.y ^ 2 + self.z ^ 2)
+    return math.sqrt(self._x ^ 2 + self._y ^ 2 + self._z ^ 2)
 end
 
-function __Vec3:to_string()
-    return "{".. self.x .. ", " .. self.y .. ", " .. self.z .. "}"
+function __Vec3:normalize()
+    local length = self:length()
+    if not length then return None end
+    return Some(Vec3 {
+        self._x / length,
+        self._y / length,
+        self._z / length
+    })
 end
 
-local v = Vec3 {1, 2, 3}
+function __Vec3:dot(other)
+    return self._x * other._x + self._y * other._y + self._z * other._z
+end
 
-print(v:to_string())
\ No newline at end of file
+function __Vec3:__tostring()
+    return "Vec3{" .. self._x .. ", " .. self._y .. ", " .. self._z .. "}"
+end