If you want to craft awesome copper blocks in Minecraft, you will first need copper ingots. You can get copper ingots very quickly in the game from copper ore that starts spawning on the overworld all the way down to the deepest reaches of the world.
However, the best place to look for copper ore would be by far around layers 47 and 48. copper also comes in two variants, deep slate copper ore, and copper ore, whereas the difference is that one can be found in deep slate while the other can not. Another is that you will need silk touch enchanted on your pickaxe, or you will not be able to mine deep slate copper ore.
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Once you find some copper ore, bring it back to your furnace and melt it down. After this, the next step to make copper blocks would be to get or make a stonecutter. You can make a stone cutter with three soild stone blocks and one iron ingot placed inside a crafting table as shown below.
When you got a stonecutter made, place it down and then turn all of your copper ingots into solid blocks by filling every space in a crafting table with them. This is how you make solid copper blocks in the game, but you can also turn these solid blocks into cut copper blocks.
To do this, place the solid copper blocks inside the stonecutter station you made earlier. After this, you will be able to craft all kinds of copper blocks, such as stairs, slabs, and regular old blocks.
For more on Minecraft, check out Where to Find a Dripleaf in Minecraft and What can you make with Copper in Minecraft?