An alternative to casting tools directly in the early game, and a requirement for higher tier metals, is to use an Anvil. An anvil is a block which can be used for two different processes: Working and Welding. This chapter is just going to show you how to obtain your first primitive stone anvil.
First, you need to acquire a block of Raw Rock, that is Igneous Extrusive (Rhyolite, Basalt, Andesite, or Dacite) or Igneous Intrusive (Granite, Diorite, or Gabbro). You could find and use an exposed block in the world, or you could extract one from the surrounding rock.
You will also need any material of Hammer. In order to make the anvil, simply right click the exposed top face of one of those raw rock blocks with your hammer, and voila! An anvil will be formed.
Anvils have tiers and the rock anvil is Tier 0 - the lowest tier. It is only able to Weld Tier I ingots.
Multiblock
Converting the center raw rock to an anvil.
In order to obtain a raw rock block without breaking it into smaller rocks, it needs to be extracted. You must mine the blocks on all six sides of a raw rock block - once it is surrounded by air on all sides - it will pop off as a item which can be picked up.
Multiblock
Mining all six sides of a piece of raw stone - once complete, the center block will pop off as an item.