Okay, so I'm writing a book and I need help. Look at details for more... well, details.
Okay, so in this book this boy is trying to prove that he's been to a parallel dimension. He is supposed to have some type of artifact, but I can't think of anything. There are a couple of rules about the artifact, though.
1. It can't be something that is already invented (fabric stronger than steel)
2. It has to fit in a pocket.
3. It has to be something inanimate
Thanks in advance for answering!