ORBITING SOLAR SYSTEM: Build eye-catchy solar system and music box at the same time. It shows the relative positions and general motions of planets. Tune: Memory MECHANICAL GEARS: No glue needed, the 3D puzzle is all connected by pins and tails. It's powered by gear trains and spring. Just wind up the key, you can see how the mechanics work. EASY TO ASSEMBLE: The package includes everything you need: illustrated manual, pre-cut wood sheets, wax for lubricant, sandpaper for polishing. Laser cutting parts is easy to pop put, and pieces fit well together. It's also friendly for new hand of 3D puzzle. NEAT DECOR, BEST GIFT.