Have a look at how I produced these doors.
This is the longest router guide I ever used… 4 meters ( 12 feet) long! An aluminium rail to which I connected the router with a home-made jig. I then routed parallel rays into the plywood, about 12 cm (5 inch) distant from each other with a V-shaped router bit.
Below, you can also see the raying completed on the left door part:
