In an effort to review all Cast Puzzles by the end of the year, this week I bring you yet another one of Hanayama's flagship products, the Cast Donuts. This is the most recent addition to the series, released in September 2011 and it was designed by the Finnish Vesa Timonen. The key word for the Donuts is "string".

The Donuts are, as the name suggests, two intertwined ring shapes that need to be separated. The solved puzzle has four pieces, as each ring is sliced in two. Figuring out how they are interlocked and what movements you need to perform is the hard part, but an experience Cast Puzzle solver will do it in no time.

I was surprised by how small this puzzle is. Most Cast Puzzles are relatively small, but this one is among the smallest ones, measuring 4.7 x 3.5cm (1.9" x 1.4"). If you have big hands, you're going to have trouble manipulating it. Another drawback, at least for me, is that the coating finish combined with its small size made it even harder to solve, as I sweat quite a bit from my hands, making it very slippery at times. Maybe a different coating with a rough surface would've helped.

(Click to Enlarge) - Partially Disassembled

Design-wise, the puzzle looks stunning. Even though it makes it slippery, the coating gives it a shiny appearance and the surface feels very smooth. In order to distinguish both rings, they were coated with two different color tones.

This is a level 4/6 rated by Hanayama and a 8/10 by PuzzleMaster. After solving the puzzle, maybe a little more than half an hour, and looking at the inner structure, I wouldn't disagree if it were classified as a level 5/6. Although experienced puzzlers won't find it that hard, casual players will struggle quite a bit to decode the right movements to separate the rings.

While looking at the puzzle for the first time, it seems pretty obvious that the lines dividing the rings are there for a reason and that they must be aligned somehow. However, it's not that simple. Giving the nature of the puzzle, it's hard to get the two parts of one ring to stay apart, while working on the other ring, without getting your fingernails inside the gaps. The first time I tried this, I ended up hurting one of my fingers with part of my fingernail chipped off. Sounds horrible, but it healed fast.

A few weeks passed before I made another attempt at solving the darn puzzle, but I was determined to get it over with. So, with more caution, there I was trying not to get another fingernail eaten by the mighty donuts. A little more than 30 minutes later, the rings were finally separated. Now, all there was left was getting the rings to their intertwined state again. It was harder than I was expecting, because when I separated them I couldn't pay much attention, as the pieces just fell down on the table. I eventually got it right in less time than I needed to solve it.

After knowing how the puzzle works and looking at the key word (string), which is supposed to be a hint, I honestly don't know how's that supposed to help in the solving process. Maybe I'm still missing something... Want a hint? - Try "slide".

Solution: Click here for a .pdf of the solution, or here for a video solution.

(Click to Enlarge)

Closing Comments:

Great concept by Vesa Timonen. The Cast Donuts is a very welcoming addition to Cast Series family, although with a couple of drawbacks regarding the design. For a level 4 puzzle, it'll put up a fight.

Availability: The Cast Donuts is available at PuzzleMaster for about $13 CAD. Click here to access the entire Hanayama Cast Series.