Thanks for the inspiration, Matt. I put this together yesterday.
It was intended as a test of the concept, and the shelf is simply an offcut of veneered MDF which was lying around (a friend gave me a several boards, which I have been using to build shop cabinets). I outlined the tools, and then free-handed the removal of waste with a power router.
https://i.postimg.cc/MTfM4kLc/Router-board1.jpg
Back in the cabinet (see earlier picks for a comparison) ...
https://i.postimg.cc/WzRFcWR5/Router-board3.jpg
It slides very nicely. I may just not bother to make another ...
https://i.postimg.cc/2y4qkQrr/Router-board2.jpg
Regards from Perth
Derek