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
Step 2: Remove the thong straps from the flip flop
using the scissors, cut away the thong portion of the flip flop
Step 3: Trace the outline of the old insole onto the flip flop
Using the sharpie, trace around the old insole onto the flip flop material.
Step 4: Cut out the insole shape
Using the scissors, cut along the line you drew in the last step. For a typical inexpensive foam rubber flip flop, this should be easy to do.
Step 5: Replace the old insole
Remove the old insole and insert this new insole in the shoe.
You might have to stuff it in a bit here and there, but it should fit snugly with room for your foot.
Step 6: Ahhh comfy!
Try it on and make sure it's okay. I find it to be very comfortable, an improvement on the old one.