Cubic Hourglasses is a concept by Bram Cohen. The puzzle has four hourglass-shaped pieces, and a three-quarter-circle piece. The object is to get the latter piece from the top to the bottom. The pieces do not only slide like in a sliding block puzzle. They also turn, pivot and skew.

Watch the YouTube video.
Read at the Shapeways Forum.
Read more at the Non-Twisty Puzzles Forum

Please contact Oskar directly if you are interested in obtaining a fully colored, stickered and assembled sample of this puzzle.