Stash Cash in the Door? - 15 Secret Hiding Places That Will Fool Even the Smartest Burglar. you know until you put it all over the Internet and then everyone and their mother knows you have secret hiding places.
This reminds me of Big Hero Self assembling robots. A team of researchers at Harvard has figured out how to get a swarm of 1024 tiny robots to work together and self-assemble into complex two dimensional shapes without anyone interfering.