I want a device which consists of a pair of lower legs and feet, jointed in the right places, modelled exactly on my own lower legs, but made of metal. When I buy new shoes or boots, I should be able to put the boots on the metal legs, turn the device on, and have the legs spend a few hours automatically running on a treadmill.

Then I'd be able to break in new footwear without getting all the bruises and blisters on my own feet. It would probably be faster, too.

(I'm at work in my old shoes today. I doubt I'll be ready to wear the new boots on a regular basis for a while yet. Ow.)