Have you ever had a shoe that was fine except that the insole came unglued from the bottom and whenever you wear it it slides around and you have to reposition it, etc.
Well, here is pretty good way to fix that on the cheap.
It should last longer than any replacement insole you could come up with and be more comfortable than the original.
Note: Because this is a thicker material, you'll have to replace the insole in both shoes, the broken one and the matching shoe as well so your feet will be at the same height when you are walking around.
Step 1: things you need
pair of flip flops (as big as or bigger than your insole) (you can often find these on sale at the end of the season for $1 a pair or so)
shoes that need a better insole
pair of good scissors