First off - I'm not a real doctor. I just hate to let shoes go just because the soles are worn through.
Years ago there was a product call Sole Saver in a Can. I bought a quart and it lasted years. Now I can't find it anymore. But I'm still wearing the soles down ( or Up?? )
Step 1: Supplies
The Sole Saver smelled like contact cement and I have this can of Scotch Grip that smells the same. This stuff is also good for gluing soles back on.
I also have a bucket of ground up rubber from car tires. I bought mine from a place called Sparton Enterprises:
I'm sure there are other rubber recycling shops. Or a re-tread tire place might give you some.
Ground rubber is also used on model railroads:
Could be a bit expensive, but you don't need much.
I found Bamboo Chop Sticks have the strength needed to spread the mix.
Step 2: The Old Shoe
These are my favorite walking and dancing shoes. Very comfortable and when they are old I still like to wear them to run toy trains. Just make sure the sole is clean, not wet or greasy.
Step 3: Mix It Up
Use disposable everything and cover your work surface because this stuff sticks!
Put a bit of the cement in the cup and then start adding the rubber slowly. When you get a good mix all the rubber should be coated, but still liquid enough to spread.
Step 4: Heavy Mixture
This was a really heavy mixture, it really taxes the strength of your mixing stick.
Step 5: Spread It ON!
Don't be shy, really work the mixture into the sole of your shoe. You have about a half hour to smooth it out. Good luck getting if off the stick and onto the sole.
Step 6: Not Too Much
This shoe wasn't too bad so just a bit filled in the bald spot. After you are done let the glue dry for a day or two. The first time you wear them the goo will compact and really get stuck.
Step 7: Major Repair
These shoe started with thin soles, so I went heavy on them.
One caution - Don't get them so thick you mess up your foot support. If they don't feel right try to adjust the shape so they feel OK. And just wear them for short trips at first to get them to dry and harden.
Good luck and I hope you can get some more wear from your favorite shoes.
Also see Dr. Quack's Easy Shoe Insoles!