Plugged Dice is a 60x60x60 mm cube puzzle (same size as Rubik's). It was suggested by Fred Horn. The object is to insert the eight plugs. This is quite a puzzle as each plug can be inserted in many ways, but the whole fits only in one way. The puzzle comes as a kit. When you buy it, you'll have to paint the cube yourself (I typically use a bath of acid-based clothing dye), and glue in the five dots.