What design pattern to use for collection of items?

I am trying to make this example as natural as possible to make it simple. Lets say I have groups of items. eg item1, item2, item3, item4 etc

currently item is represented by struct

// only contains data
struct item{
  string name;
  std::vector<string> parts_name;
  std::vector<double> parts_price;
  std::vector<string> item_color;
  ...
};

itemx item1, item2...

Then I have class called items

class items{
  public:
  // return name of all items
  vector<string> get_all_item();

  // return price of all parts 
  vector<string> get_all_parts_price();  

 private:
  // hold vector of item
  vector<shared_ptr<item>> list_of_items;

  // name of item and its parts price
  // eg: <item_1_part_1, $1.3>
  // eg: <item_1_part_2, $2.3>
  // eg: <item_2_part_1, $4.3>
  map<string, double>  parts_prices;

};

The problem with my current items class is that it is growing really huge, as feature of item increases.

My solution :

make struct item contain function which distributes load to struct item from class items.

Is there any other better way or any design pattern that is meant for this kind of problem?