There are already several reviews of the Dice Box by puzzle collectors/bloggers Oliver Sovary-Soos and Brian Pletcher, so you can read their experiences with the original wooden version. There's even a video uploaded by PuzzleboxWorld.
While not in wood nor crafted by Kamei himself, the plastic version by Hanayama is no less of a nice puzzle. While I have not played with the wooden version, I am confident that Hanayama, as a reputable Japanese manufacturer of puzzles would have faithfully followed the design of Kamei in coming up with an inexpensive version of what is a collector's (and very expensive) copy of the Dice Box.
My copy measures a smaller size of 5.6cm cube all round, about a third of the size of its wooden cousins. As far as quality is concerned, no issues here. The plastic feels solid and the sliding panel that opens the box slides smoothly with little free play. The inside bottom of the box is even lined with a piece of red felt, such attention to detail. Obviously for a plastic version which is significantly cheaper than the original, the pips (or dots) here are printed on the six surfaces as opposed to the wooden version which has recessed holes and contrasting woods.
What is strange is that unlike the wooden original, the Hanayama version comes already solved, ie with the lid open. I would think the wooden version is harder, since it comes closed and being a Kamei creation, finding the panel that slides would already be a challenge in itself. As John Rausch said:
"The Die is one of Kamei's most famous secret opening boxes. Familiarity with the spots on a normal die will help you discover the first clue to opening it. The objective is find a way into the secret compartment that is shown in the 2nd photograph. The mechanism is outstanding. Perhaps the best of any Kamei box"
The object of my copy is to close the lid, give it a good shake, turn it around in all directions (to activate the locking mechanism) and then try to open the lid again. I did precisely these and found the lid shut tight. Sounds of moving parts can be heard inside the puzzle and the trick is to figure how to solve the mechanism which unlatches the sliding top. As you can't see what goes on inside (nor the mechanism) even when the lid is opened, there is little clue offered as to how to go about solving the Dice Box once shut.
So the initial stages of play consisted of random tilting and and turning of the box and even some light tapping (from the Japanese instructions on the box, I could not tell if there was something to indicate "no tapping/banging"). I have some experience with hidden mechanism puzzle boxes and I tried a couple of methods to see if these did the trick. After several minutes of play, suddenly the lid slid open by itself! I am not exactly sure what I had done correctly, but I had a rough idea of the moves needed to repeat the result. The next several attempts resulted in easy solves. I knew what needed to be done, but only had a vague idea of how the mechanism inside worked. I was able to repeat solve most of time using the sequence of moves which I assume to be correct.
The plastic Dice Box (in several colour variations) is available from Amazon and Ebay from between $14/- to $40/- while the Kamei-made wooden ones, in excess of $150/- are available from PuzzleboxWorld and Art Of Play.