DNA is said to be the building block of life, and atoms and molucules are the building blocks of matter. This may well be the building block of a happy childhood. I had lots of these as a kid, mind you never this size.
You are looking for a unique container the size of a small, but the actual cache within is the size of a micro containing just a log, so BYOP. Please take care when replacing the hide, so others may enjoy the same experience.
Cheers!