Why not make shoes out of shoe goo?
put a condom on each of your feet and pour away.
Isn't that what Crocs are made out of? All kidding aside, you could but it's really expensive, so they use other polymers to make shoes from.
Definatly when you've got the bottom of your shoes smooth on the heel and toe areas. If you get holes in the sides where they hit your toes, instead of buying a whole new pair you can go to cvs and buy shoe goo. Put some of that on the holes and they'll be good as new. Shoe goo got my old lakai's to last almost a year.