It's not really "unbelievably difficult" , as some suggested (took me about 45 min overall to solve it), but it does require some thinking on how it might be made inside. This is one of the few "logical" puzzles, where you can just guess the internal structure and act accordingly. If you don't, it may indeed appear "unbelievably difficult". For some reason, solving this one reminded me lock-picking techniques -- it's the same kind of approach. It doesn't look as cool as some other puzzles, but is definitely worth cracking :)

Very disappointed in this one. The construction is not up to par with other Hanayama puzzles. The nuts on mine are so loose that you can 'cheat' the puzzle apart without solving it. In addition, the looseness gives a huge visual cue as to the solution. A five minute puzzle at our house. Perhaps this is from a bad lot and a better made copy would have been a worthy contender.

Giving it a 3. There is no "trick" in this one. And although its sturdy, mine had some binding and didn't turn well in some places. Fairly simple to deduce inner workings after a quick glance... its just a matter of lots of trial and error... and patience for 5-60min of fiddling. Ironically, solved first time in 5min, and showing to friend took almost and hour to disassemble. There is also alternate solution if your puzzle happens to be well worn in which was my first attempt ;)

Fairly simple puzzle. I was a little disappointing that it only took a few minutes to figure this one out. I thought it may be a fluke that i figured it out so quick so i brought it to work. 3 other people were able to solve it under 15 minutes. Nice puzzle but not a level 10.

Good looking puzzle. Not a hard solve.. Mine just came apart with some fiddling. I was hoping for some heavier metal. Feels light like cast disk...Not my fav...

I'm sort of on the fence about this one. Fairly interesting concept for a puzzle, but I don't like the fact that there was so much trial and error involved.

This is my favorite one. Very difficult, but possible.

I found this to be easier than I expected compared to some other 6 star Hanayamas. I'd recommend it as a 'beginner' level 10.

So. I thought it was incredibly hard... several Google engineers tried it without success - but I gave it to an artist friend of mine and she solved it in a few minutes without the internet (but then, she spends a heck of a lot of time with bolts...)

Unbelievably difficult and the solution is not intuitive. Not recommended.

This was quite hard, but i didn´t like it as much as the other 6 star Hanayamas.