Version:

Contenttweaker allows you not only to add single items to the game but whole materials! You can for example use these materials to automatically generate a new ore together with gears, ingots and the like!

There are 5 Terms that are important:

Material: The Material you are going to add/use (e.g. Platinum) → What the items are made of
PartType: Basically a group (e.g. Block, Item, Entity, etc) → The type of the parts
Part: The item’s form (e.g. Gear, Rod, Ingot, etc)
MaterialPart: Combination of Part and Material (e.g. Iron rod, Platinum Gear, etc) → Can be used to return the item as IItemStack later on.
MaterialPartData: Some configurations → Varies by part type, check the wiki page for further information.

Example Script

  #loader contenttweaker
  //////////
  // Calls
  //////////
  import mods.contenttweaker.MaterialSystem;
  import mods.contenttweaker.Material;

  //////////////
  // Variables
  //////////////
  var copper = MaterialSystem.getMaterialBuilder().setName("Copper").setColor(15766817).build();
  var tin = MaterialSystem.getMaterialBuilder().setName("Tin").setColor(10275286).build();
  var silver = MaterialSystem.getMaterialBuilder().setName("Silver").setColor(15592941).build();
  var lead = MaterialSystem.getMaterialBuilder().setName("Lead").setColor(5658219).build();
  var cobalt = MaterialSystem.getMaterialBuilder().setName("Cobalt").setColor(18347).build();

  var metal_list = [copper, tin, silver, lead, cobalt] as Material[];
  var part_names = ["dust", "gear", "plate", "nugget", "ingot", "beam", "bolt"] as string[];
  var ore_types = ["ore", "poor_ore", "dense_ore"] as string[];

  ///////////////////////////
  // Material registration
  ///////////////////////////

  for i, metal in metal_list {
      metal.registerParts(part_names);

      var ores = metal.registerParts(ore_types);
      for i, ore in ores {
          var oreData = ore.getData();
          oreData.addDataValue("variants", "minecraft:stone,minecraft:end_stone,minecraft:netherrack");
          oreData.addDataValue("hardness", "3,3,3");
          oreData.addDataValue("resistance", "15,15,15");
          oreData.addDataValue("harvestTool", "pickaxe,pickaxe,pickaxe");
          oreData.addDataValue("harvestLevel", "1,1,1");
      }

      var blockData = metal.registerPart("block").getData();
      blockData.addDataValue("hardness", "5");
      blockData.addDataValue("resistance", "30");
      blockData.addDataValue("harvestTool", "pickaxe");
      blockData.addDataValue("harvestLevel", "1");
  }

Contenttweaker Material System

Example Script