This. is. magic.
Physical motion—pushing a button, laundry soap flowing out of a bottle, turning a knob, removing a hammer from a weighted tool bench—triggers gears and springs elsewhere in the 3-D printed object that cause a conductive switch to intermittently connect or disconnect with the antenna and change its reflective state. Information—in the form of 1s and 0s—is encoded by the presence or absence of the tooth on a gear. Energy from a coiled spring drives the gear system, and the width and pattern of gear teeth control how long the backscatter switch makes contact with the antenna, creating patterns of reflected signals that can be decoded by a WiFi receiver.