Precision devices dodecagon routing

If you want the cut out to be the full depth of the first sheet of ply, it might be easier to do it with a jigsaw. If you're only going the depth of the driver, put the driver inverted on the ply and draw around, then with ideally a small palm router and some guide rails (I usually use a 2' or 4' spirit level).. on a scrap of timber, make a rough cut from the guide with your chosen router bit and check the distance from the outside edge of the cut to the rail. Clamp the rails to the outside face this distance from the line you drew and route them out. This is okay of you're only doing a few. If I had more than two to do, I'd jigsaw out a template jig (hole) that was the distance you measured bigger than the cut out you want (+ maybe 2mm) on a scrap piece of 18mm, clamp this to the face and away you go. I'm sure others have other and maybe more practical options...

Thanks for the reply, I was going to go through the full thickness of the front panel, would I need a small diameter straight router bit, as the corners of a PD dodecagon aren't particularly rounded? 

Put your driver with magnet up, on a table. Build a template out of pieces of wood boards by placing them around the drivers edge and screw them together.

Always birch no matter what. Why use hardwood at all?