Fun Territory Defense by the Optimistic Lord summary:
The man who reincarnated as a noble boy Van grows up to be treated as a child prodigy after efforts, but when he is known to have "production magic", he is driven to the lord of a remote village. However, the magic called useless is just out of the standard that you can produce anything as long as you have the materials! With the knowledge of the previous life and cheat magic, a small and poor village will grow into a huge city―― !?