I needed a lock nut for my bike peddals, but only had a normal nut. So I bought Elmer's rubber cement and painted the bolt and let it dry. Following day, I put the bolt on and wa-la, it worked.
Step 1: Easy Cheap Lock Nuts
I find nuts on my walls all the time so they are free
I buy rubber cement at the cheap stores
Step 2: Easy
paint the inner threads of the nut then screw it on the bolt.