As the name implies, there is a hidden trick inside the cylinder puzzle. There is absolutely no hint or clue on how to start from the outside appearance. If there is one hint that we can provide, it is to go about it as if you were cracking open a safe. Enjoy finding the solution while pretending to be a spy cracking open a safe with a shaken not stirred martini by your side. The theme is "lock".This is the description for "Cast Cylinder". When I first got it, I truly pretended that I was trying to open a safe. And what else could be done - with the inner structure of the puzzle not visible, you can only rotate the five pieces around until any of them is moved to an unexpected position. It is very intriguing to play with this puzzle, especially if you are into puzzles which do not give any hint how to be solved. Personally, I think I don't mind puzzles where there is something hidden inside and the only way to solve it the first time is by luck. Why should I? After all, the other Hanayama Cast puzzles which are similar to this are among my favourites - Cast Nutcase, Cast Marble, Cast News, Cast Delta, Cast Square. They all have this feature in common - there is something inside, hidden in or between the pieces, which is part of the solution, and which you have to figure out by yourself, if you have never faced it before.
I was impressed by the inner structure of "Cast Cylinder". It is something that requires time to come up with and even more time to experiment with before having a final version. The three inner pieces are created precisely so that they can fit in the other two and still there is room for some unexpected moves (be it part of the correct path of the solution or dead-ends). After opening it, you can inspect the pieces carefully and find out how and why the solution works. Thus, on your next goal you can do it much faster and with ease. OR, you can just try to put it back together without paying attention to the details and have the fun again the next time you go for separating the pieces. It is up to you.
Finally, here is how I rate "Cast Cylinder":
Difficulty: 4. I was not sure whether it should be 4 or 5. But I would agree with Hanayama's rating here, simply because there is not strictly just one solution - there are some variations on what is done first and one can solve it in alternate ways, just as I did on my first success.
I would recommend "Cast Cylinder" to puzzlers who have at least one puzzle in their collection.