diff --git a/src/ship/items/inventory.rs b/src/ship/items/inventory.rs
index c949d74..a44c97d 100644
--- a/src/ship/items/inventory.rs
+++ b/src/ship/items/inventory.rs
@@ -240,6 +240,13 @@ impl InventoryItem {
         }
     }
 
+    pub fn stacked_mut(&mut self) -> Option<&mut StackedInventoryItem> {
+        match self {
+            InventoryItem::Stacked(ref mut stacked_inventory_item) => Some(stacked_inventory_item),
+            _ => None
+        }
+    }
+
     pub fn mag(&self) -> Option<&Mag> {
         match self {
             InventoryItem::Individual(individual_inventory_item) => individual_inventory_item.mag(),
@@ -477,6 +484,23 @@ impl CharacterInventory {
         }
     }
 
+    pub fn stack_item_id(&self, tool: &Tool) -> Option<ClientItemId> {
+        self.items.iter()
+            .filter_map(|item| {
+                match item {
+                    InventoryItem::Stacked(s_item) => {
+                        Some(s_item)
+                    },
+                    _ => None
+                }
+            })
+            .find(|s_item| {
+                s_item.tool == *tool
+            })
+            .map(|item| {
+                item.item_id
+            })
+    }
 
     pub fn get_item_handle_by_id(&mut self, item_id: ClientItemId) -> Option<InventoryItemHandle> {
         let (slot, _) = self.items.iter()
@@ -571,10 +595,57 @@ impl CharacterInventory {
             .next()
     }
 
-    pub fn add_item(&mut self, item: InventoryItem) -> Result<(), InventoryAddError> { // TODO: errors
-        // TODO: check slot conflict?
+    pub fn take_stacked_item_by_id(&mut self, item_id: ClientItemId, amount: usize) -> Option<StackedInventoryItem> {
+        let idx = self.items
+            .iter_mut()
+            .position(|i| i.item_id() == item_id)?;
+        let item: &mut StackedInventoryItem = self.items.get_mut(idx)?.stacked_mut()?;
+        match item.entity_ids.len().cmp(&amount) {
+            Ordering::Equal => {
+                let item = self.items.remove(idx);
+                item.stacked().cloned()
+            },
+            Ordering::Greater => {
+                let entity_ids = item.entity_ids.drain(..amount).collect();
+                Some(StackedInventoryItem {
+                    entity_ids,
+                    tool: item.tool,
+                    item_id: item.item_id,
+                })
+            },
+            Ordering::Less => {
+                None
+            }
+        }
+    }
+
+    pub fn add_item(&mut self, item: InventoryItem) {
         self.items.push(item);
-        Ok(())
+    }
+
+    pub fn add_stacked_item(&mut self, mut item: StackedInventoryItem) {
+        let existing_item = self.items
+            .iter_mut()
+            .filter_map(|i| {
+                match i {
+                    InventoryItem::Stacked(stacked) => {
+                        Some(stacked)
+                    },
+                    _ => None
+                }
+            })
+            .find(|i| {
+                i.tool == item.tool
+            });
+
+        match existing_item {
+            Some(existing_item) => {
+                existing_item.entity_ids.append(&mut item.entity_ids)
+            },
+            None => {
+                self.items.push(InventoryItem::Stacked(item))
+            }
+        }
     }
 
     pub fn add_individual_floor_item(&mut self, floor_item: &IndividualFloorItem) -> &InventoryItem {