So to facilitate the training of camp attendees (and design engineers) next summer, I purchased many different puzzle boxes in Hakone to use as teaching tools.
These products of Hakone are exquisitely designed wooden boxes with inlaid intricate images in complex patterns that mask the secret panels that are the key to eventually gaining access to the contents inside.
The same fundamentals apply in opening puzzle boxes from Hakone, Japan: something appears impossible to circumvent until you figure out the secret, and locks, just like the secret boxes, are all about hidden secrets.