This is going to be a quick guide on the settings/required modifications to use the rotary module with Lightburn.
I am sorry, but it will require following the beginning of my full lightburn control guide. Mainly flashing the custom firmware (as of writing, make sure you’re on the latest 1.14.3 before loading the custom firmware and do NOT turn the machine off until it’s done).
Follow along until the GCode header/footer section, for the rotary you only need M3 S0 in the header, and M5 in the footer.
In this guide, my equipment used is as follows;
Machine: Snapmaker 2.0 A350
Tool: 1.6W Laser
Accessory: Rotary Module
Material: Cherry wood.
Software: Lightburn 1.3.01 (current as of writing)
After following the above guide until the header/footer as outlined, you should now have a machine with custom firmware, and the snapmaker setup as a GRBL M3 with M3 S0 header and M5 footer.
First step is going to be enable the rotary in Lightburn, this is done by opening the menu Laser Tools and clicking Rotary Setup. This will open a window with the Rotary options. Set them as follows, except for the material diameter, this will of course be set to your own material size.
Ticking the Enable Rotary button of course, enables output for rotary. In my testing, the Mirror Output was required, else it was flipped in the X axis. Since the rotary is its own axis and not an extension of another (like a bed roller), we select A, since it works in degrees. This is the main Lightburn settings, but keep in mind there IS minimal gcode modifications necessary after export.
When you begin to setup a project, it will have to be rotated 90 degrees, so sideways in the view. As an example of using this image (internet find, not my photo):
Rotate 90 degrees into the corner like this:
The reason for this is, it seems Lightburn expects an X axis laid chuck instead of the snapmaker’s Y laid chuck. So with the rotary active, it moves in X/A. We’ll be reversing it so it moves in Y/B. If you look at the black and white image, it swaps X with Y and Y with B. So B will scan up/down, and Y left/right in the preview, but opposite on the rotary. (basically imagine looking at the snapmaker from the touchscreen side.)
While not required, it’s optional to change the scan angle. At default 0, it will move Y for the scanning, and the rotary for the interval. You can modify the scan angle to 90 degrees to have the rotary do the scanning, and Y do intervals. Settings for the example are as follows, though I should have reduced the laser power to maybe 75%)
These settings, of course, depend on your projects and tests. 
Try a -45 degree scan so Y AND B have to work together. The final setting you will need in Lightburn is use Center Left as your origin. This will make your origin the tailstock end with the image center on the laser. Use Top Left to make the image scan right of where you put the dot, or Bottom Left to make it scan left. In my example, I just used center.
That’s it! Your project is ready to export, yes, export. There’s some modifications to be done before it can run. Currently you will have to run the project via the touchscreen, as I haven’t tested/figured out full control for origins yet. But I’ve got some ideas, so stay tuned. Click the Save Gcode button while you’re at it to save the file to your desktop. If it’s the first time you’re saving gcode, when you’re inputting the name, make sure it ends in .nc, Lightburn might try using .gc first.
Open the resulting .nc file in your favorite text editor, I used Notepad++ in this example. You will need to simply replace A with B and X with Y. It might take awhile, it finds thousands of lines. 
Click save, place the .nc file onto the USB, and shove it into the snapmaker. Start it as you would any normal file, remember your origin is going to be toward the tailstock so it’ll start there, and work towards the chuck.
That’s it! Hopefully this leads to many of you getting cleaner and faster projects, or taking this base guide and coming up with your own ideas on how to improve. Maybe make a post-process batch script to do the replacements for you.
As always, I’ll try to answer any questions to the best of my ability. I’ll go ahead and answer this one; no, don’t trust the preview. It seems to draw in the opposite direction. Remember, we flipped X and Y, that’s why it’s wrong.
