If you read my earlier post about "Spy’s exploding monkey dung (and more) for sale" I told you about some historical spy gear for sale. If you want something a bit more affordable, there’s this 3/4" diameter bolt that can hold small items (the storage compartment is .49" in diameter with a depth of 2.7".) If you can squeeze your spy data onto a MicroSD card, you’ve got yourself a high-tech hiding place.
Buy your own bolt at Shomer-Tec>>