An excellent inside maze puzzle that will have you wracking your brain as to how to open it.  There are 3 mazes in this puzzle.  Each one is different.  Each one is smaller in size. 
There are lots of dead ends on this puzzle so don't feel bad if you don't get it right away.
It's tough just being able to look at the maze and solving it.
3D Printed Maze Puzzle

• See at Puzzle Master