The C-Shell is a 3D printed plastic packing puzzle designed by Alexander Magyarics and made by Rex Rossano Perez.  The goal is to insert the pieces within the frame as to leave no exposed gaps.  Rotations and straight movements required.  There is one unique solution.
Difficulty: 16 moves (8.5.3) The brackets indicate the breakdown of moves to fit each piece sequentially.
 

• See at Puzzle Master