Submitting is still an option for you. You just need to fill in some of the fields and then make sure to have "Do not list this module" checked. This option is tailored to your need:
Check this field if you do not want your module to be listed in the module browser. It will be excluded from the module search, too. This is useful for your unique DIY modules and alternations of modules already in the database, technically considered as duplicate.
The Machine: https://www.modulargrid.net/e/racks/view/1601144