Examine the old collar and make notes of how it is put together.

Lay the collar out flat and measure the length. Then take an old pair of jeans and cut a strip from the hem or inseam to match the measurement.

You can trim up the strip and add some anti fray stuff if you don't like the frayed look.

Now take the old collar and remove the hardware.

Put the hardware on the denim strip the way it was put together on the old collar and use your trusty hot glue gun to glue down the ends to keep everything in place. Don't forget to poke a little hole in the denim where the thingie (very technical term) goes through. (Like a belt)

Now let your faitful friend rock a rustic look. The hot glue holds very well, I haven't had any problems and he's been wearing it for about a month now, even on the leash.