Summary

if you choose to buy a low cost Crocs like (please plrefer the real one : Crocs are very good)
This is to repair it...

Instructions

one weak point is the back part which breack at the rivet area.
I have designed 2 pieces to repair.
In my case the rivet is not broken that's why I've design in 2 pieces.

Let's Go :

Print the set.
mount the male one on the inner side of the broken part,punch a little hole to put the male part through.
Then mount the female on the outer side (put it in a mirrror position to have a close loop - not an open hook)
Use a flame to meld the pin
That's done.

5 minutes to repair.

Crocs like repair parts