On Windows, use qBitTorrent's [Torrent Creator](https://www.ghacks.net/2019/09/20/how-to-create-a-private-torrent-using-qbittorrent/)
On Linux (CLI), use [`ctorrent`](http://manpages.ubuntu.com/manpages/bionic/man1/ctorrent.1.html). (Like: `ctorrent -t -s output_file.torrent /path/to/source/dir`)