diff --git a/Metaballs.xcodeproj/project.pbxproj b/Metaballs.xcodeproj/project.pbxproj
index 86b4b1d..e088bf5 100644
--- a/Metaballs.xcodeproj/project.pbxproj
+++ b/Metaballs.xcodeproj/project.pbxproj
@@ -9,6 +9,7 @@
 /* Begin PBXBuildFile section */
 		C03904B31F43CF3F00C74022 /* PreferencesWindowController.swift in Sources */ = {isa = PBXBuildFile; fileRef = C03904B11F43CF3700C74022 /* PreferencesWindowController.swift */; };
 		C09161701F3F5AE6009C4263 /* PreferencesViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = C091616F1F3F5AE6009C4263 /* PreferencesViewController.swift */; };
+		C0B906D51F45432700B5F89B /* Preferences.swift in Sources */ = {isa = PBXBuildFile; fileRef = C0B906D41F45432700B5F89B /* Preferences.swift */; };
 		C0BBE36B1F2E816500E68524 /* AppDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = C0BBE36A1F2E816500E68524 /* AppDelegate.swift */; };
 		C0BBE36D1F2E816500E68524 /* ViewController.swift in Sources */ = {isa = PBXBuildFile; fileRef = C0BBE36C1F2E816500E68524 /* ViewController.swift */; };
 		C0BBE36F1F2E816500E68524 /* Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = C0BBE36E1F2E816500E68524 /* Assets.xcassets */; };
@@ -47,6 +48,7 @@
 /* Begin PBXFileReference section */
 		C03904B11F43CF3700C74022 /* PreferencesWindowController.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = PreferencesWindowController.swift; sourceTree = "<group>"; };
 		C091616F1F3F5AE6009C4263 /* PreferencesViewController.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = PreferencesViewController.swift; sourceTree = "<group>"; };
+		C0B906D41F45432700B5F89B /* Preferences.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = Preferences.swift; sourceTree = "<group>"; };
 		C0BBE3671F2E816500E68524 /* Metaballs.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = Metaballs.app; sourceTree = BUILT_PRODUCTS_DIR; };
 		C0BBE36A1F2E816500E68524 /* AppDelegate.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AppDelegate.swift; sourceTree = "<group>"; };
 		C0BBE36C1F2E816500E68524 /* ViewController.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ViewController.swift; sourceTree = "<group>"; };
@@ -160,8 +162,9 @@
 				C0BBE3A31F2E81C700E68524 /* Metaballs.swift */,
 				C0CE7BFF1F362C3F001516B6 /* Geometry.swift */,
 				C0DF1D781F3789DC0038B0A0 /* Memory.swift */,
-				C03904B11F43CF3700C74022 /* PreferencesWindowController.swift */,
+				C0B906D41F45432700B5F89B /* Preferences.swift */,
 				C091616F1F3F5AE6009C4263 /* PreferencesViewController.swift */,
+				C03904B11F43CF3700C74022 /* PreferencesWindowController.swift */,
 			);
 			path = MetaballsKit;
 			sourceTree = "<group>";
@@ -382,6 +385,7 @@
 			files = (
 				C03904B31F43CF3F00C74022 /* PreferencesWindowController.swift in Sources */,
 				C0DF1D791F3789DC0038B0A0 /* Memory.swift in Sources */,
+				C0B906D51F45432700B5F89B /* Preferences.swift in Sources */,
 				C0BBE3A41F2E81C700E68524 /* Metaballs.swift in Sources */,
 				C0CE7C001F362C3F001516B6 /* Geometry.swift in Sources */,
 				C09161701F3F5AE6009C4263 /* PreferencesViewController.swift in Sources */,
diff --git a/MetaballsKit/Preferences.swift b/MetaballsKit/Preferences.swift
index e1536d6..439af3d 100644
--- a/MetaballsKit/Preferences.swift
+++ b/MetaballsKit/Preferences.swift
@@ -8,8 +8,51 @@
 
 import Cocoa
 
-class PreferencesWindowController: NSWindowController {
-    override func prepare(for segue: NSStoryboardSegue, sender: Any?) {
-        print("prepare for segue:\(segue), sender:\(String(describing: sender))")
+extension UserDefaults {
+    var color0: Float4? {
+        get {
+            return float4(forKey: "color0")
+        }
+        set {
+            set(newValue, forKey: "color0")
+        }
+    }
+
+    var color1: Float4? {
+        get {
+            return float4(forKey: "color1")
+        }
+        set {
+            set(newValue, forKey: "color1")
+        }
+    }
+
+    var color2: Float4? {
+        get {
+            return float4(forKey: "color2")
+        }
+        set {
+            set(newValue, forKey: "color2")
+        }
+    }
+
+    var color3: Float4? {
+        get {
+            return float4(forKey: "color3")
+        }
+        set {
+            set(newValue, forKey: "color3")
+        }
+    }
+
+    func float4(forKey key: String) -> Float4? {
+        guard let values = array(forKey: key) as? [Float], values.count >= 4 else {
+            return nil
+        }
+        return Float4(values[0], values[1], values[2], values[3])
+    }
+
+    func set(value: Float4, forKey key: String) {
+        set([Float](float4: value), forKey: key)
     }
 }