[blueridger]

While this type of installation is not new, I could not find a DIY. Hopefully others will find this information helpful. This is also my first time creating a DIY, so be kind. You can use this to mount any type of LED display inside the mirror. i.e. Radar-mirror offers custom mirrors that include PLX gauges. Or, in areas where radar detectors are allowed, this might be a good way to mount the display.

No etching was involved...simply remove part of the gray plastic, then use an Exacto knife to trim the black material from the back of the mirror. A little Goo Gone cleans off any remaining adhesive. The display vanishes when turned off yet shows through beautifully when turned on.