I have created a simple design in DesignSpark Mechanical, saved that design as an OBJ file. In Cura I load that OBJ file. I click on the button that says "Prepare". It does this just fine, tells me how long (estimated) to print. Then I click 'Save to File' and Cura just quits. It doesn't create the gcode file the 3D printer needs. Anyone have any suggestions on what I'm doing wrong? Thanks. P.S. Never printed anything before in my life. Would just like to see it work. Cura 3.4.1 and Monoprice mini 3D printer v2. Cura keeps saying 'Not connected to printer', so I'm just trying to save the gcode file to the micro SD card.