I received this e-mail from one of my athletes in Kona preparing for the Hawaiian Ironman:
Bad news – My new custom, casted orthotics which arrived last week are not good; got a big blister on the lateral side of my left foot.
I wrote back:
See if you can duct tape your foot in the area of the hot spot. (Of course cover the blister so the duct tape doesn't tear the skin off.) Baby powder or talc the edges of the tape to keep the sticky stuff from gathering dirt.
Blisters not a problem ... love the duct tape.
This foot care trick is used often by ultrarunners and hikers.