Martinet doesn't offer a GUI because Martinet's input is a text file and Martinet's output is an email. Any program like this which has a GUI ends up being little more than diagrams — text in bubbles connected by lines. This doesn't suit what one can do with Martinet's syntax (consider the ACE entry requirements for table filtering syntax, for example).

Perhaps there is room for a Martinet configuration file editor website which offers interactive GUI editing. Such an editor will require considerable design and implementation time.