I have small circuits that are easily drawn in Fritzing or other CAD PCB tool.
I found tools that can import Gerber files (generated by Fritzing or not) and export G-Code, so theoretically it would be possible to create CAD in many other PCB designs and then generate the G-Code for GRBL / Arduino.
CopperCAM is one of these tools but requires that it be created an appropriate G-Code profile for GRBL / Arduino through the Post Processor. This is not an easy task for those unfamiliar with G-Code.
As the Fritzing be early, get a G-Code compatible with GRBL / Arduino it is also in development but if it is possible other tools beyond Fritzing will benefit from it.