diff --git a/src/main/java/net/knarcraft/knargui/item/AbstractGUIItemFactory.java b/src/main/java/net/knarcraft/knargui/item/AbstractGUIItemFactory.java
index da6cce5..8349736 100644
--- a/src/main/java/net/knarcraft/knargui/item/AbstractGUIItemFactory.java
+++ b/src/main/java/net/knarcraft/knargui/item/AbstractGUIItemFactory.java
@@ -15,7 +15,7 @@ import java.util.function.Consumer;
  * @param <B> <p>A child class implementing this class</p>
  */
 @SuppressWarnings("unused")
-public abstract class AbstractGUIItemFactory<B extends AbstractGUIItemFactory<B>> {
+public abstract class AbstractGUIItemFactory<B extends AbstractGUIItemFactory<B>> implements GUIItemFactory {
 
     private final ItemStack itemStack;
     private B child;
@@ -37,45 +37,30 @@ public abstract class AbstractGUIItemFactory<B extends AbstractGUIItemFactory<B>
      *
      * @param child <p>The child class extending this</p>
      */
-    protected void setChild(B child) {
+    protected void setChild(@NotNull B child) {
         this.child = child;
     }
 
-    /**
-     * Builds the item as described in previous calls
-     *
-     * @return <p>The output of this factory</p>
-     */
+    @Override
+    @NotNull
     public ItemStack build() {
         return this.itemStack;
     }
 
-    /**
-     * Sets the name of this factory's item
-     *
-     * @param name <p>The new item name</p>
-     * @return <p>The factory. Used for chaining commands</p>
-     */
-    public B setName(String name) {
+    @Override
+    @NotNull
+    public B setName(@NotNull String name) {
         return changeItemMeta((meta) -> meta.setDisplayName(name));
     }
 
-    /**
-     * Sets the lore for this factory's item
-     *
-     * @param lore <p>The new lore</p>
-     * @return <p>The factory. Used for chaining commands</p>
-     */
-    public B setLore(List<String> lore) {
+    @Override
+    @NotNull
+    public B setLore(@NotNull List<String> lore) {
         return changeItemMeta((meta) -> meta.setLore(lore));
     }
 
-    /**
-     * Sets whether this factory's item should look enchanted
-     *
-     * @param enchanted <p>True if the item should look enchanted</p>
-     * @return <p>The factory. Used for chaining commands</p>
-     */
+    @Override
+    @NotNull
     public B setEnchanted(boolean enchanted) {
         if (enchanted) {
             changeItemMeta((meta) -> meta.addEnchant(Enchantment.MENDING, 1, true));
@@ -87,25 +72,15 @@ public abstract class AbstractGUIItemFactory<B extends AbstractGUIItemFactory<B>
         }
     }
 
-    /**
-     * Changes some metadata for this factory's item
-     *
-     * @param action <p>The action to be run on the metadata</p>
-     * @return <p>The factory. Used for chaining commands</p>
-     */
-    protected B changeItemMeta(Consumer<ItemMeta> action) {
+    @Override
+    @NotNull
+    public B changeItemMeta(@NotNull Consumer<ItemMeta> action) {
         return changeItemMeta(ItemMeta.class, action);
     }
 
-    /**
-     * Changes some metadata for this factory's item
-     *
-     * @param metaType <p>The type of metadata to change</p>
-     * @param action   <p>The action to be run on the metadata</p>
-     * @param <M>      <p>The type of the metadata</p>
-     * @return <p>The factory. Used for chaining commands</p>
-     */
-    protected <M extends ItemMeta> B changeItemMeta(Class<M> metaType, Consumer<M> action) {
+    @Override
+    @NotNull
+    public <M extends ItemMeta> B changeItemMeta(@NotNull Class<M> metaType, @NotNull Consumer<M> action) {
         M meta = checkForNullMetadata(metaType);
         action.accept(meta);
         this.itemStack.setItemMeta(meta);
@@ -115,12 +90,9 @@ public abstract class AbstractGUIItemFactory<B extends AbstractGUIItemFactory<B>
         return child;
     }
 
-    /**
-     * Throws an exception if this factory's item has null metadata
-     *
-     * @return <p>The metadata for this factory's item</p>
-     */
-    protected <M extends ItemMeta> M checkForNullMetadata(Class<M> metaType) {
+    @Override
+    @NotNull
+    public <M extends ItemMeta> M checkForNullMetadata(@NotNull Class<M> metaType) {
         M meta = metaType.cast(this.itemStack.getItemMeta());
         if (meta == null) {
             throw new IllegalArgumentException("Cannot change missing metadata");
diff --git a/src/main/java/net/knarcraft/knargui/item/GUIItemFactory.java b/src/main/java/net/knarcraft/knargui/item/GUIItemFactory.java
index 4a8f701..adb3b92 100644
--- a/src/main/java/net/knarcraft/knargui/item/GUIItemFactory.java
+++ b/src/main/java/net/knarcraft/knargui/item/GUIItemFactory.java
@@ -1,43 +1,77 @@
 package net.knarcraft.knargui.item;
 
-import org.bukkit.Material;
 import org.bukkit.inventory.ItemStack;
+import org.bukkit.inventory.meta.ItemMeta;
+import org.jetbrains.annotations.NotNull;
+
+import java.util.List;
+import java.util.function.Consumer;
 
 /**
- * A class for crating visual items for the GUI
+ * A factory class for creating GUI items
  */
 @SuppressWarnings("unused")
-public class GUIItemFactory extends AbstractGUIItemFactory<GUIItemFactory> {
+public interface GUIItemFactory {
 
     /**
-     * Instantiates a new item factory
+     * Builds the item as described in previous calls
      *
-     * @param material <p>The material to use for the new item</p>
+     * @return <p>The output of this factory</p>
      */
-    public GUIItemFactory(Material material) {
-        super(new ItemStack(material, 1));
-        setChild(this);
-    }
+    @NotNull
+    ItemStack build();
 
     /**
-     * Instantiates a new item factory
+     * Sets the name of this factory's item
      *
-     * @param material <p>The material to use for the new item</p>
-     * @param amount   <p>The number of items to be displayed</p>
+     * @param name <p>The new item name</p>
+     * @return <p>The factory. Used for chaining commands</p>
      */
-    public GUIItemFactory(Material material, int amount) {
-        super(new ItemStack(material, amount));
-        setChild(this);
-    }
+    @NotNull
+    GUIItemFactory setName(@NotNull String name);
 
     /**
-     * Instantiates a new item factory
+     * Sets the lore for this factory's item
      *
-     * @param itemStack <p>The item stack to modify</p>
+     * @param lore <p>The new lore</p>
+     * @return <p>The factory. Used for chaining commands</p>
      */
-    public GUIItemFactory(ItemStack itemStack) {
-        super(itemStack);
-        setChild(this);
-    }
+    @NotNull
+    GUIItemFactory setLore(@NotNull List<String> lore);
+
+    /**
+     * Sets whether this factory's item should look enchanted
+     *
+     * @param enchanted <p>True if the item should look enchanted</p>
+     * @return <p>The factory. Used for chaining commands</p>
+     */
+    @NotNull
+    GUIItemFactory setEnchanted(boolean enchanted);
+
+    /**
+     * Changes some metadata for this factory's item
+     *
+     * @param action <p>The action to be run on the metadata</p>
+     * @return <p>The factory. Used for chaining commands</p>
+     */
+    @NotNull
+    GUIItemFactory changeItemMeta(@NotNull Consumer<ItemMeta> action);
+
+    /**
+     * Changes some metadata for this factory's item
+     *
+     * @param metaType <p>The type of metadata to change</p>
+     * @param action   <p>The action to be run on the metadata</p>
+     * @param <M>      <p>The type of the metadata</p>
+     * @return <p>The factory. Used for chaining commands</p>
+     */
+    @NotNull <M extends ItemMeta> GUIItemFactory changeItemMeta(@NotNull Class<M> metaType, @NotNull Consumer<M> action);
+
+    /**
+     * Throws an exception if this factory's item has null metadata
+     *
+     * @return <p>The metadata for this factory's item</p>
+     */
+    @NotNull <M extends ItemMeta> M checkForNullMetadata(@NotNull Class<M> metaType);
 
 }
diff --git a/src/main/java/net/knarcraft/knargui/item/PlayerHeadGUIItemFactory.java b/src/main/java/net/knarcraft/knargui/item/PlayerHeadGUIItemFactory.java
index 116f23f..83c83d7 100644
--- a/src/main/java/net/knarcraft/knargui/item/PlayerHeadGUIItemFactory.java
+++ b/src/main/java/net/knarcraft/knargui/item/PlayerHeadGUIItemFactory.java
@@ -6,6 +6,7 @@ import org.bukkit.OfflinePlayer;
 import org.bukkit.inventory.ItemStack;
 import org.bukkit.inventory.meta.SkullMeta;
 import org.bukkit.profile.PlayerProfile;
+import org.jetbrains.annotations.NotNull;
 
 import java.net.MalformedURLException;
 import java.net.URL;
@@ -37,7 +38,8 @@ public class PlayerHeadGUIItemFactory extends AbstractGUIItemFactory<PlayerHeadG
      * @param player <p>The player whose skin should be used</p>
      * @return <p>The factory. Used for chaining commands</p>
      */
-    public PlayerHeadGUIItemFactory useSkin(OfflinePlayer player) {
+    @NotNull
+    public PlayerHeadGUIItemFactory useSkin(@NotNull OfflinePlayer player) {
         return changeItemMeta(SkullMeta.class, (meta) -> meta.setOwningPlayer(player));
     }
 
@@ -47,7 +49,8 @@ public class PlayerHeadGUIItemFactory extends AbstractGUIItemFactory<PlayerHeadG
      * @param playerProfile <p>The player profile whose skin should be used</p>
      * @return <p>The factory. Used for chaining commands</p>
      */
-    public PlayerHeadGUIItemFactory useSkin(PlayerProfile playerProfile) {
+    @NotNull
+    public PlayerHeadGUIItemFactory useSkin(@NotNull PlayerProfile playerProfile) {
         return changeItemMeta(SkullMeta.class, (meta) -> meta.setOwnerProfile(playerProfile));
     }
 
@@ -57,7 +60,8 @@ public class PlayerHeadGUIItemFactory extends AbstractGUIItemFactory<PlayerHeadG
      * @param uuid <p>The UUID of the skin to use</p>
      * @return <p>The factory. Used for chaining commands</p>
      */
-    public PlayerHeadGUIItemFactory useSkin(UUID uuid) {
+    @NotNull
+    public PlayerHeadGUIItemFactory useSkin(@NotNull UUID uuid) {
         return useSkin(Bukkit.getOfflinePlayer(uuid));
     }
 
@@ -71,7 +75,8 @@ public class PlayerHeadGUIItemFactory extends AbstractGUIItemFactory<PlayerHeadG
      * @param textureId <p>The id of the texture to use</p>
      * @return <p>The factory. Used for chaining commands</p>
      */
-    public PlayerHeadGUIItemFactory useSkin(String textureId) {
+    @NotNull
+    public PlayerHeadGUIItemFactory useSkin(@NotNull String textureId) {
         //Get the texture id from a Base64 encoded JSON string
         if (!textureId.isBlank() && textureId.length() % 4 == 0) {
             String decoded = new String(Base64.getDecoder().decode(textureId));
@@ -94,7 +99,8 @@ public class PlayerHeadGUIItemFactory extends AbstractGUIItemFactory<PlayerHeadG
      * @param url <p>The URL to use</p>
      * @return <p>The factory. Used for chaining commands</p>
      */
-    public PlayerHeadGUIItemFactory useSkin(URL url) {
+    @NotNull
+    public PlayerHeadGUIItemFactory useSkin(@NotNull URL url) {
         PlayerProfile profile = Bukkit.createPlayerProfile(UUID.randomUUID());
         profile.getTextures().setSkin(url);
         return changeItemMeta(SkullMeta.class, (meta) -> meta.setOwnerProfile(profile));
diff --git a/src/main/java/net/knarcraft/knargui/item/SimpleGUIItemFactory.java b/src/main/java/net/knarcraft/knargui/item/SimpleGUIItemFactory.java
new file mode 100644
index 0000000..e18607a
--- /dev/null
+++ b/src/main/java/net/knarcraft/knargui/item/SimpleGUIItemFactory.java
@@ -0,0 +1,44 @@
+package net.knarcraft.knargui.item;
+
+import org.bukkit.Material;
+import org.bukkit.inventory.ItemStack;
+import org.jetbrains.annotations.NotNull;
+
+/**
+ * A class for crating visual items for the GUI
+ */
+@SuppressWarnings("unused")
+public class SimpleGUIItemFactory extends AbstractGUIItemFactory<SimpleGUIItemFactory> {
+
+    /**
+     * Instantiates a new item factory
+     *
+     * @param material <p>The material to use for the new item</p>
+     */
+    public SimpleGUIItemFactory(@NotNull Material material) {
+        super(new ItemStack(material, 1));
+        setChild(this);
+    }
+
+    /**
+     * Instantiates a new item factory
+     *
+     * @param material <p>The material to use for the new item</p>
+     * @param amount   <p>The number of items to be displayed</p>
+     */
+    public SimpleGUIItemFactory(@NotNull Material material, int amount) {
+        super(new ItemStack(material, amount));
+        setChild(this);
+    }
+
+    /**
+     * Instantiates a new item factory
+     *
+     * @param itemStack <p>The item stack to modify</p>
+     */
+    public SimpleGUIItemFactory(@NotNull ItemStack itemStack) {
+        super(itemStack);
+        setChild(this);
+    }
+
+}