Romain Chauliac has recently updated his PlugIt script for Maya which now allows to add custom plugs.
For those of you unfamiliar with the tool, it allow artists to add details when working on hard surface models.
In one click, the tool lets you add plugs to your mesh. Users also get control over scale, rotation, connection, and more. The artist states that it works both with flat and curvature shapes.
The good news is that the newest version adds the ability to create your own plugs in seconds.
Please note that PlugIt is only working in Maya 2018 and higher. You can learn more here.