You can get the same result as the Aunt Becky by getting an old thimble at the thrift or antique store. It is a silver/nickel color thimble that the dimples around the top are relatively smooth. Hammer the round top flat so you have a good sharp edge. Works just like the Aunt Becky.
I have used the Aunt Becky and don't really like it. Had a quilting friend that said she threw it acros the room several times before she got the hang of it. Some might also use a regular small spoon for the same results. I have more control with the modified thimble.