First lets say you found an iron ore and you smelted it. Now you have one iron ingont. Go to your crafting table and turn the ingot into a block then turn the block back into an ingot. You should get nine ingots. Now put 8 of th em in your chest. Now with the 1 ingot go to the craftinh table and turn that one into a block reapeat umtil u get how much you want. Also works with gold and diamonds.