You’ve moved the goal posts.
It’s not that the construction of some thing, anything, that can be used to write with is difficult. As you point out a piece of charcoal isn’t hard to make.
Milton Friedman’s point is that even something as simple and inexpensive as a pencil involves people all over the world working together to create it. Some mine graphite, some run ships to move the graphite, some manufacture paint, some grow rubber trees, etc. All of this activity, coordinated and made efficient by the market is behind even a simple thing like a pencil.