I finally got all my dimmers paired. I used Varilight push button switches for mains and then mounted the Tradfri switches over the top. Using velcro to mount the plates (so as backup you can still access the mains switch).
Gives a very clean non DIY look. I used white plate as all my other sockets and switches are from the same Varilight range. But you can use the silver to give some contrast. Velcro gives just enough clearance (few mm) for the push button not to touch the plate. Then the Tradfri switch sits on top with the included magnets.
IMO much better look then the HUE dimmers with 3D printed mounting plate.