Copper and Tin have a few uses. Copper can be crafted into wires, with the ability to be insulated using rubber. Combinations of rubber and tin are used in making batteries.
The ores can be ground using a Macerator. By combining the resulting copper and tin dust in the crafting table with a ratio of three copper to one tin, one can obtain bronze dust, which can be smelted into bronze ingots. When you mix 3 Tin Ingots with 3 Refined iron Ingots and 3 Bronze Ingots, you get 2 Mixed Metal Ingots.
Copper and Tin dust can also be crafted into a small pile of iron dust, two of which will result in iron dust, which can then be smelted down into iron.