Help needed to print from Cura to our MP mini delta 3D printer via MacBook

[tomsmiled 0]

Hi

We are trying to 3D print using a Mono Price mind delta 3D printer, from a MacBook (OS 10.13.6). We know the printer works as the demo model (a cat, saved as a .g file) prints. The printer only prints .g files, we understand.

My son designed a building block a la Lego using Autodesk Fusion 360, and saved as a .stl file. We opened in Cura to slice. But we can't seem to save as a .g file; the nearest option appears to be .gcode. Printer won't print this. We tried manually changing the file name to .g. Printer recognised this, started to work (we thought), but stopped after less than a second. And nothing else happened.

Have we got a software problem (or doing something wrong), or a hardware problem? Or is this a Mac OS interface problem?

Would you need more information to make a diagnosis?

Any advice or troubleshooting tips would be very much appreciated.