I wanted to create a "child zone" that would be activated by kids.

The "Child Zone" is active whenever a face is detected (no smile necessary), but the face must be not more than 46 inches from the ground and the face must be facing the AIY camera. 

A 3d printed "U shape" bracket holds the photoresistor above the Google AIY vision kit's lamp. The bracket can be taped to the AIY cardboard box.

The 3d printed housing for the AIY kit involves a box with a hole to hold the kit and a "blinder shelf" that limits the camera's upward visibility while providing a seat for a decorative elf.

The box is mounted to the wall using a wood screw, then the AIY kit is placed inside.

The seat/blinder is placed on top of the box (a 3 mm screw on the back can be used to tighten the seat), then an elf is place atop the platform.

For "smiling Mrs. Claus" there is a sign that says "Smile :) Mrs. Claus Smiles Back." My current thinking is that the child zone will be unmarked--a discovery area. It should be fun to see if "word gets around" that there is a hidden activation zone.