Also list all extra custom hard drives in the creative tab.

src/main/java/li/cil/oc2/common/bus/device/data/BlockDeviceDataRegistry.java

@@ -12,6 +12,7 @@ import net.minecraftforge.registries.RegistryObject;
 
 import javax.annotation.Nullable;
 import java.util.function.Supplier;
+import java.util.stream.Stream;
 
 public final class BlockDeviceDataRegistry {
     private static final DeferredRegister<BlockDeviceData> INITIALIZER = RegistryUtils.create(BlockDeviceData.class);
@@ -38,4 +39,8 @@ public final class BlockDeviceDataRegistry {
     public static BlockDeviceData getValue(final ResourceLocation location) {
         return REGISTRY.get().getValue(location);
     }
+
+    public static Stream<BlockDeviceData> values() {
+        return REGISTRY.get().getValues().stream();
+    }
 }

src/main/java/li/cil/oc2/common/item/AbstractBlockDeviceItem.java

@@ -85,4 +85,10 @@ public abstract class AbstractBlockDeviceItem extends ModItem {
             return super.getName(stack);
         }
     }
+
+    ///////////////////////////////////////////////////////////////////
+
+    protected ResourceLocation getDefaultData() {
+        return defaultData;
+    }
 }

src/main/java/li/cil/oc2/common/item/HardDriveWithExternalDataItem.java

@@ -3,14 +3,18 @@
 package li.cil.oc2.common.item;
 
 import li.cil.oc2.api.API;
+import li.cil.oc2.common.bus.device.data.BlockDeviceDataRegistry;
 import li.cil.oc2.common.util.ColorUtils;
 import net.minecraft.Util;
+import net.minecraft.core.NonNullList;
 import net.minecraft.resources.ResourceLocation;
+import net.minecraft.world.item.CreativeModeTab;
 import net.minecraft.world.item.DyeColor;
 import net.minecraft.world.item.DyeableLeatherItem;
 import net.minecraft.world.item.ItemStack;
 
 import javax.annotation.Nullable;
+import java.util.Objects;
 
 public final class HardDriveWithExternalDataItem extends AbstractBlockDeviceItem implements DyeableLeatherItem {
     private final int defaultColor;
@@ -25,6 +29,20 @@ public final class HardDriveWithExternalDataItem extends AbstractBlockDeviceItem
 
     ///////////////////////////////////////////////////////////////////
 
+    @Override
+    public void fillItemCategory(final CreativeModeTab tab, final NonNullList<ItemStack> items) {
+        super.fillItemCategory(tab, items);
+
+        BlockDeviceDataRegistry.values().forEach(data -> {
+            if (!Objects.equals(BlockDeviceDataRegistry.getKey(data), getDefaultData())) {
+                final ItemStack stack = withData(data);
+                if (!stack.isEmpty()) {
+                    items.add(stack);
+                }
+            }
+        });
+    }
+
     @Override
     public int getColor(final ItemStack stack) {
         return hasCustomColor(stack) ? DyeableLeatherItem.super.getColor(stack) : defaultColor;