This is not what you think it is.
When you hear "Box Puzzle" you probably picture yourself a box that opens secretly, with
a sophisticated lock inside which you cannot see and you have to guess blindly
what it is.
Our box puzzles are nothing like that. In fact we are surprised that nobody ever thought
that a puzzle can have an interesting internal shape.
All our Box Puzzles are interlocking puzzles with an empty space inside.
The hollow space inside can be used for putting a little surprise in!
This is where the interesting part comes in: Another puzzle can fit perfectly inside the
first one! This is how the Hard Nut set was born.
Hard Nut set.
In fact, almost any of the well constructed symmetrical puzzles can have empty space in
it. Even members of the very solid looking Magic Crystal family,
have cube-like cavities in them.
the Magic Crystal family.
And all The Quad Squad partners can have Octahedrons in them.
The Quad Squad partners.
The difference is how much solid material is left
between the outside and inside space. The record-breaker in this contest is the "Skin
Octacube" which is nothing but a thin layer of plastic or even cardboard. And it
holds a Cubic Octahedron inside which seems to have the same size.