From a discussion on the Makergear 3D printer forums …
From a new M2 user disillusioned by the learning curve:
Is there a 3D CAD software out there that natively creates .g or .gcode files It’s not just a 3D printing thing.
CAD (computer-aided design) software produces a solid model, which a CAM (computer-aided manufacturing) program then converts into the specific dialect(s) of G-Code required by whatever machine tool(s) will create the widget. You can create the solid model using many different CAD programs and convert it into G-Code with many different CAM programs, each with its own collection of features and warts.
3D printing calls the CAM program a “slicer”, but it’s a different name for the process of converting geometry into machine instructions.
Even in subtractive manufacturing using lathes and mills, you absolutely must understand how the G-Code interacts with the production hardware.
I unfortunately don’t want to learn all the nuances and parameters of the slic3r software
Then you must use a service like Shapeways: you create the model, send it to them, and get a neat widget a few days later. Their laser-sintered powder process provides much better built-in support than you’ll ever get from consumer-grade fused-filament printers, you can select from a wide variety of materials (including metals!), and, as long as you follow their straightforward design guidelines, you’ll never know how the magic happens.
If you intend to create more than a trivial number of widgets, though, the cost in both cycle time and money will begin gnawing at you. In round numbers, I’ve been designing and printing one widget a week for the last seven years, so adding a printer to my basement shop and learning how to use it has been a major win.
The Smell of Molten Projects in the Morning 
though after some years of fiddling, 95% of my prints use Cura 3’s canned configurations on the simple “Recommended Settings” tab. This allows you to change layer height and infill, plus on/off settings for support and build plate adhesion. Having less to mess with when starting up means less initial discouragement and fewer wasted prints. One shouldn’t have to know all the details to start off. The details will come if there’s interest.
Makergear might do well to get a canned configuration shipped with Cura. I’m even a fan of the way that Windows 10 has built 3d printing into its printer subsystem – though I haven’t quite managed to get anything sensible printed from it yet. It seems to be trying to print the printer self test page.
After I figured out what the M2 likes, it’s pretty much pushbutton simple: build a model, send to Octoprint, print, done! My settings are weird, but they work for me.
Makergear apparently has a deal with (whoever makes) S3D to have them inculde a reasonable set of defaults, but it’s obvious software isn’t MG’s core competency. In all fairness, though, supporting the cross product of all slicers / materials / printer versions would be a support nightmare of the first water.
All newbies, myself included, eventually wedge themselves into a corner with All Wrong Settings and can’t get back out. I think it’s part of the learning process, because 3D printing still isn’t a civilian-friendly process.
Why am I not surprised? On the other paw, if there existed a standard test object, being able to print it would be a great confidence builder. If it worked, of course! [grin]