Today’s invention is an electronically simulated mirror with special features. This would contain a camera system capable of detecting a face appearing in front of the screen.
This screen could be set to display the camera’s moving image of the person appearing in front of it, as usual. The invention would be to store a variety of movies of different people in front of their mirrors.
When your mirror ‘saw’ your face, it could detect the presence of eg hands and eyeblinks, smiles and nods and display those elements extracted and stitched together from someone else’s stored reflection (in the right places, very nearly in realtime and smoothed together to create the illusion of lifelike movements).
If you wanted always to see yourself as you were ten years ago, then this would be possible (using recorded footage or that of an avatar, based on some stills and a regression algorithm). You could even choose to view yourself as an ancestor, perhaps or a celebrity. This might also help people who had been disfigured to regain some confidence.