Shoe stores once let customers watch the bones move inside their own feet, right through an X-ray machine built into the shopping experience.

From the 1920s through the 1950s, shoe-fitting fluoroscopes stood in stores across America, the UK, and beyond. A shopper would slide a foot into a candidate pair of shoes, step into a wooden cabinet, and look down through a viewing port to see a glowing green image of their skeleton, foot bones fitted inside the shoe's outline. Parents especially loved them, convinced this was the scientific way to check whether a growing child had enough room to spare.

At their peak in the late 1940s, more than 10,000 of these machines were fitting shoes in stores nationwide. Salespeople operated them dozens of times a day, often holding the beam steady on a customer's foot for a better look, with little more than a wooden cabinet between them and the X-ray tube.

Nobody was tracking dosage. Machines varied wildly in calibration, some leaking far more radiation than intended, and repeated exposure for salespeople and frequent shoppers eventually raised alarm as scientists learned more about the cumulative dangers of radiation. 

States began banning the devices in the late 1940s, and by the early 1970s the shoe-store X-ray had vanished entirely, leaving behind a handful of survivors now sitting quietly in museum collections.