Buy at https://www.shapeways.com/model/2536991/plus-pieces-for-geared-mixup-plus.html Copyright (c) 2014, M. Oskar van Deventer. Geared Mixup Plus is a shape-mod of the Geared Mixup. It was requested by Carl Hoff and a few other people. Geared Mixup is a twisty puzzle with 18 gears. That puzzle has hidden spacers between the geared pieces. The plus pieces are extensions of those spacer pieces all the way up to the cube surface of the puzzle, so they can be stickered. This adds another dimension of difficulty to an already very difficult puzzle.
