Perfect Fit ?
Well, I'm really gonna show my age here but this is almost science fiction - certainly unbelievable by today's standards.
They used to have these machines in shoe stores. After the correct style and fit had apparently been made, final confirmation was made by stepping up on the platform of this podium and putting your feet, proudly encased in their new footwear, into the slot where they would be subjected to a dose of X-Ray for a final see through view.
It seemed cool because you could look into the special viewing portal and see your toes right through the shoes ! This podiatric peep show left no doubt if proper clearance and fit was achieved.
Needless to say, the health hazards* made this tool short lived, but it remains permanent part of my earliest shoe shopping memories.
* measurements performed during the late 1940s indicated that the doses to the feet ranged from 7 to 14 R for a 20 second exposure...surveys at the time indicated that more than 60 percent of inspected machines exceeded the American Standards Association recommendation of 2 R to the feet per five second exposure.
More Info:Shoe-Fitting Fluoroscope