Set your stars out in the size and grid you want. Put an extra rectangle around the stars. Highlight all the stars and the rectangle. Go to tools, pocket cut. Pick a fine bit 1/16” or so to pocket with and also select use larger bit for clearance and use 1/4 or 1/8 depending on your project size.
When you calculate and preview you will see the background in the rectangle is carved away, the stars are left proud.