Hard pens are divided into pens, pencils, ballpoint pens and so on. What is the purpose of writing hard-pen calligraphy? If it's an exhibition or something, I suggest you use an art pen, but I must remind you that writing with a brush looks good, doesn't it? But not everyone can use brushes well, and so can art brushes. People who can't use art brushes well can write in a grandiose and unorganized way, but they can't cover everything in one word. If you haven't used an art brush for a while, I suggest you don't use it. In fact, the ordinary pen is the most practiced kung fu. I suggest you use an ordinary pen, and you can use black ink. As long as the kung fu is deep, the pen is secondary. As for carbon, you can certainly use it after you have mastered the basic skills of hard pen calligraphy, but it is not suitable for writing exhibitions.
There is no shortcut to calligraphy, but iron inkstone is the best way to sharpen it.
If you have any questions about calligraphy, I hope you can discuss and communicate with each other.