diff --git a/storage/itemgroup.lua b/storage/itemgroup.lua
new file mode 100644
index 0000000..955410b
--- /dev/null
+++ b/storage/itemgroup.lua
@@ -0,0 +1,151 @@
+local ItemGroup = {}
+ItemGroup.__index = ItemGroup
+
+--- Create a group of managed itemstacks
+---@param stack table ItemStack to compare to
+---@return table ItemGroup instance representing stack type
+function ItemGroup:from(stack)
+    local obj = { stack }
+    setmetatable(obj, self)
+    obj.__index = obj
+    return obj
+end
+
+function ItemGroup.collectStacks(stacks)
+  local groups = {}
+  for _,stack in ipairs(stacks) do
+    for _,group in ipairs(groups) do
+      if group:addStack(stack) then
+        goto continue
+      end
+    end
+    table.insert(groups, ItemGroup:from(stack))
+      ::continue::
+  end
+  return groups
+end
+
+function ItemGroup:getStackCount()
+  return #self
+end
+
+function ItemGroup:getDisplayName()
+  return self:_getIdentityStack():getDisplayName()
+end
+
+function ItemGroup:getName()
+  return self:_getIdentityStack():getName()
+end
+
+function ItemGroup:getEnchantments()
+  return self:_getIdentityStack():getEnchantments()
+end
+
+function ItemGroup:_getIdentityStack()
+  return self[1]
+end
+
+function ItemGroup:_iterateStacks()
+  return ipairs(self)
+end
+
+function ItemGroup:_addStack(stack)
+  table.insert(self, stack)
+end
+
+function ItemGroup:_removeStack(stackOrIndex)
+  if type(stackOrIndex) == "number" then
+    return table.remove(self, stackOrIndex) ~= nil
+  else
+    for index,stack in self:_iterateStacks() do
+      if stack == stackOrIndex then
+        return self:_removeStack(index)
+      end
+    end
+  end
+end
+
+function ItemGroup:canAddStack(stack)
+  if self:_getIdentityStack():canTransfer(stack) then
+    for _,chkStack in self:_iterateStacks() do
+        if chkStack == stack then
+            -- Already in the group
+            return true
+        end
+    end
+    self:_addStack(stack)
+    return true
+  end
+  return false
+end
+
+function ItemGroup:addStack(stack)
+  if self:canAddStack(stack) then
+    self:_addStack(stack)
+    return true
+  end
+  return false
+end
+
+function ItemGroup:getItemCount()
+  if self:_getIdentityStack():isEmpty() then
+    return 0
+  end
+  local sum = 0
+  for _,stack in self:_iterateStacks() do
+    sum = sum + stack:getCount()
+  end
+  return sum
+end
+
+function ItemGroup:_copyTrackedStackList()
+  local collect = {}
+  for index,stack in self:_iterateStacks() do
+    table.insert(collect, { stack = stack, index = index })
+  end
+  return collect
+end
+
+function ItemGroup:defragment()
+  if self:_getIdentityStack():isEmpty() then
+    return 0
+  end
+
+  local entries = self:_copyStackList()
+  table.sort(entries, function(a, b)
+    return a.stack:getCount() > b.stack:getCount()
+  end)
+  local endPtr = #entries
+  local startPtr = endPtr
+  for i=1,endPtr do
+    local entry = entries[i].stack
+    if entry:getMaxCount() ~= entry:getCount() then
+      startPtr = i
+    end
+  end
+
+  local toRemove = {}
+  while startPtr < endPtr do
+    local from = entries[endPtr]
+    local to = entries[startPtr]
+
+    local emptied, _ = from.stack:transferTo(to.stack)
+    if emptied then
+      table.insert(toRemove, from.index)
+      endPtr = endPtr - 1
+    end
+
+    if (not emptied) or (to.stack:getCount() == to.stack:getMaxCount()) then
+        startPtr = startPtr + 1
+    end
+  end
+
+  table.sort(toRemove, function(a, b) return a > b end)
+  for _,index in ipairs(toRemove) do
+    self:_removeStack(index)
+  end
+
+  return #toRemove
+end
+
+return ItemGroup
\ No newline at end of file