The Onion puzzle is indeed shaped and looks almost like a real onion, but much smaller at around 13/4 inches in diameter and 11/4 inches thick. It is made of the material that Shapeway describes on their site as "White, Strong, Flexible & Polished". I believe it to be some sort of resin or plastic (although I cannot be sure). The puzzle is well manufactured and all the pieces fit properly and are nice and smooth (important for the Onion). Whatever the material is, it feels tough and durable, although the white colour tends to stain quite easily.
The object of the puzzle is to "peel" the layers of the Onion out from inside the shell...unlike a real onion. My Onion arrived in a solved state; ie all the 5 inner pieces were already separated. It was not overly difficult to fit the pieces together back inside the shell but removing them again was much more challenging. Certainly not that easy at all and I grappled with the puzzle for a good while before finally removing all the inner pieces. As with any puzzle, there is a way to solve the Onion without using any force or extraction tools.
|Vesa Timonen's Onion dwarfed by its real cousin|
Overall the Onion is a decent looking puzzle, pretty unusual I would say (both in name and design), against the plethora of puzzles out there. From the puzzling aspect, it also poses a reasonable challenge.