Find or create a mandala for the pattern. I did use a free mandala from pixabay, but I did edit it to follow their license rules. 

Set the design to engrave.

I also added an outline of +1 and moved it to another layer to score it. This gives the whole pattern a fuller look.

For the baseplate you want to add a circle to the canvas in the size of 298x298

Add another circle to the canvas in the size of 298x298 and add a negative outline of -15 to it. 
Select both circles and “Combine → Substract at overlap” to create a ring.

For the top plate you want to add a circle with the size of 240x240.

Add 33 smaller circles with the size of 13.5x13.5 and place them in the shape of a +

Adjust the settings so that they fit your material and your desired engraving result and send the file to your laser machine.

If you use 3mm plywood like I did, you will have to cut the ring and the top plate twice (just cut the top plate, don't engrave it a 2nd time).

You can also use 6mm plywood with adjusted settings.

Now glue all the pieces together using wood glue. Wait until it is fully dry and enjoy your game.