EagleCad slots and board outlines

I am designing a quadrotor board. It sonsists of a main board with 2 gyros and a daughterboard for the Yaw gyro. The idea is to make a lip on the daughter board and a slot on the main board and solder/glue the two together!

I think I figured out how to change the board outline by redrawing the outlines defined in the “dimension” layer. It looks correct, but I am not sure it this is the right way to do it?

I also need to make a slot on the main board to mate with lip on daughter board. How is this done. Do I just define a rectangle on the milling layer, or is there a better way to do it?

Thanks

Jussi

You’ll need to ask the fab shop how they want it. A lot of the 1-off pcb houses can’t do internal cuts.