Is it permissible to trade in industrial materials sold to craftsmen, knowing that their point of sale is only a few meters away from my shop, and that the intention to trade preceded my arrival in the city?

It is not permissible to prevent anyone from trading in what is permissible, due to the Almighty’s saying: "Allah has permitted trade and forbidden usury," and due to the saying of the Prophet, peace and blessings be upon him: "Leave the people; Allah provides for some of them through others." It is not permissible for merchants to monopolize a certain commodity and prevent others from trading in it. It is permissible for the ruler to regulate buying and selling, just as it is permissible for merchants to agree among themselves on regulating their buying and selling, but it is not permissible for some of them to prevent others or restrict others without mutual consent. Therefore, there is no impediment to your selling of these materials.