This section is all about puzzles that confront you with obvious challenges but hidden problems. Open them, unlock them, disassemble them, with little or no guidance as to how. You can go by past experience with this genre, and/or raw intuition - sometimes careful observation helps, too - but these puzzles are designed to be real stumpers. You can't really attack them with computers. Many of them, particularly the puzzle boxes, are objects of art. This is one of my favorite categories.

I'd have to say that the Alcatraz Puzzle is a great representative of this category. It started life as a magic trick but it makes a great puzzle (so few magic tricks really do). U.S. Patent 4625968 - McDermott 1986	The Cage Rage looks similar but is much bigger and has a completely different mechanism. You are unlikely to solve it without help - it comes with video taped solution instructions. U.S. Patent 5944311 - Hartzell 1999	My Dad made me a Pyramid of his own design, containing sand in its mechanism!
SEARious burr from Mr. Puzzle Australia	From Davan's, a Lili (really nice wood, but impossibly difficult!)	This is "Bi-Polar" from Orb Factory
This brass Treasure Box is a Rocky Chiaro design from B&P. It has a very tricky mechanism, demanding multiple steps to open and close.	This brass cannon from B&P is an affordable version of a design that appeared in Hoffmann's Puzzles Old and New.	Danzig's Dilemma is similar to the Sandfield Joint.
My friend Dr. Ralph Marlett has his own metal lathe and he made me this trick-opening cylinder I call "Elegance" because of its inscription.	The Citadel Not really hidden-mechanism, but certainly a plethora of confusing doohickies to manipulate in an effort to free the red ball.	The Yin-Yang Ball Open it. Not difficult. Could be filed under Boxes, or Magnetic.
These designs are by Jean-Claude Constantin. Remove the "Yen Coin" (just a washer in this version). You've Been Framed B and P Bolted Closed pyramid in prison U324 - Adjust the levers and remove the central triangular prism.
The Prison Block from BandP	This is Great Escape from Mag-Nif. It's plastic but the same as the Prison Block.	This is a Dowel-and-Peg puzzle from Tom Lensch
This "Triple Dovetail Triangle" from R.D. Rose (Mental Block Puzzles) is beautifully executed in aluminum. (R.D. Rose passed away in December of 2007.)	Three Bar Cube - B & P	Stuck Bolt - B & P
Fish Torpedo	Mysterious Ball	Gelenk Separate the two pieces.
I have seen this called a "Zwaalustaart." It is very similar to the Sandfield Joint.	This is Hexaspiration, presented by Edward Hordern at IPP13. Remove the rod from the hexagonal cylinder.	Coin Safe A nice brass rendition of a puzzle described in Hoffmann - sold as a magic trick.
Here are some secret-opening puzzles by Frank Chambers made from Corian material. (Frank Chambers passed away in July of 2007.) The Captive Coin - a copy of a design in Hoffmann. Presented by Edward Hordern at IPP14. Wheel and Axle - Frank Chambers Get the Ball Out - Frank Chambers Ring Box - Frank Chambers Match Box - Frank Chambers Introduced by Peter Hajek at IPP27
Block and Key - Rossetti - IPP22	Cigar - Gillen - IPP23	Lost Luggage Bits and Pieces 2005
Entangled Fish - B & P	Scroll Puzzle - Doug Engel	Pyr-Eye-Mid
Impossicube - Markus Goetz (B & P)	Egg (NYPP 2007)	Deja Vu - Puzzlemaster
Thomas Beutner's Tangled Dovetail - IPP26	Brian Young's Gold Coast Parking Meter - IPP27

The first three have been sold in a set (I don't have) called "The Masterpiece Puzzles."

The Penny Safe and the Marble Safe are two instances of the same puzzle which has also appeared as a trick-opening match safe (vesta).

This is an 1893 White City Puzzle Bank: 

It is not so much a hidden-mechanism, as it is a "missing mechanism" puzzle - one is supposed to present it without the wing-nut, which slips onto the central spindle and allows it to be unscrewed. Without the wing-nut, you're screwed.

These puzzles are all made in Germany by the mysterious R.D. also known as "Roger." They are made from machined aluminum blocks and other metal elements, and each harbors a secret.

I have seen them at:

• Hendrik Haak's Puzzle-Shop
• Arabesk
• J.C. Constantin

The Lighter (Feuerzeug) A very clever take on an old principle.	Schraubenwuerful	Schluessel
	The Propeller	007 Shaker
Gesicht	Geburt
Eis	Auspuff (I don't have this.)
Wasserhahn	Stecker (I don't have this.)	Gartenschlauch (I don't have this.)
Mastercard (I don't have this.)	Cylinder (I don't have this.)
	R2D2 (Appears in my Dexterity section.)	Alles Roger (Appears in my Dexterity section.)

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This Wil Strijbos design is an example of what I consider to be the first of three "classic" trick bolt mechanisms. I got mine from Puzzletts in Seattle. Here is a link to an article on homemetalshopclub.com on how to make one (scroll to the bottom).	Eureka Nut and Bolt This is the second "classic" mechanism - less mechanical, more trick. This piece is hefty and well-made.	This German-made bolt is of the third "classic" design - a different (and fairly obvious) trick.
	I don't know who made this bolt, but it is a faithful implementation of the design described on page 113 in Anthony S. Filipiak's 1942 book 100 Puzzles - How to Make and Solve Them. See U.S. Patent 1111337 - Watkins 1914
This Wil Strijbos design was my first. I figured out how to get it apart but I can never manage it without a tool.	This is another Wil Strijbos design. I "cheated" by using an external object. Then I found that the required tool is in the puzzle - but again, it is very hard to get at the tool without a tool.	This is the vintage Nut and Bolt Puzzle No. 9655 by B. Shackman. It uses the first classic trick.
My friend Ralph Marlett made this bolt for me. It employs the first classic mechanism.	I include this nail-thru-coin from B&P here since it exploits a thread. (Did I just give away too much?)	This is the "Holey Bolt" from B&P - it is really more of a tanglement (and I show it on that page, too) but it does involve a nut and bolt - in this case, though, try to get the nut on!
The CAST Extra Nut Puzzle is a refinement of classic mechanism 2.	Here are three additional designs by Wil Strijbos. All the Strijbos bolts look similar, but are very different.
This is NANAB (Not Another Nut And Bolt) by Frank Chambers. presented at IPP17.	A bolt on a hanger.	The smaller of these is the Perplexagon. I also have a larger version. A thread is cut in the middle of a steel rod, but not to either end. How did the nut get on? Can you get the nut off?

There are people, such as the physicist Richard Feynman, who consider normal combination locks and some padlocks to be puzzles in and of themselves. Locks with trick mechanisms usually present a more reasonable challenge and do not require lockpicking skills. Many are made in India and China.

This is a DanLock I got from Dan Feldman. In puzzle circles it's widely acknowledged to be the "Rolls Royce" of trick locks.	The Lunatic Lock from B&P - nicely made in aluminum. A maze of internal sliding pins.	4-step Chinese Puzzle Lock from Puzzleboxesusa (defunct?)
B&P called this "Lockout" but the box says Kishor Trick Lock. It's made in India.	Here is a hefty multi-step puzzle lock, from India. Purchased from Lee Valley and Veritas Tools.	Another Indian puzzle lock. Very simple trick - a theme amongst this type.
Trick Lock (or Cigar Cutter) aka the Bashful Lock "I will open behind your back" See U.S. Patent 1136735 - Taylor 1915	The Sherlock	Lockout by Irwin More of a game than a puzzle - One person devises a "code" and a second tries to solve it
Neat Lock - Hajek IPP23	Mikslok - Chambers IPP20	Eleganter Australia Antique Lock Puzzle Made in China - package says Neko Mook No. 708 PET
This is an "Utterly Unique Puzzling Padlock" purchased from Frik-n-Frak's Curio Shack.	Heart Lock - B&P	Sparten Lock
Chaman Lock	plastic lock - McDonald's premium	two puzzle locks by Marcel Gillen
a Chinese combination lock	A trick lock engraved "MIOf[]"	a small "springy" lock
Diamond lock from India	Key-shaped Lock from India	Chronos Trick Locks #1 and #2 Purchased from Torito. #1 is the same mechanism as the Lunatic Lock. #2 is different.
Trick Locks #1, 2, 3, 4, and 5 (left to right) from Puzzlemaster

• Here is Matthias Hass' site on locks. It's huge!
• Here is some info on Chinese puzzle locks.
• Puzzlemaster sells some puzzle locks from India

The Sandfield brothers Norman and Robert have designed several clever trick-opening puzzles using an impossible dove-tail theme. The craftsman Perry McDaniel has made many of them. Norman was kind enough to supply to me a complete list of the puzzles he and his brother have produced over the years for the IPP. (Several photos from John Rausch's site.)

IPP14 held in 1994 in Seattle, Washington Ever since I got this Sandfield Joint puzzle years ago (from Puzzletts in Seattle, I think), I've wanted another Sandfield puzzle. In my opinion this is a classic, combining a trick dovetail joint with an internal hidden trick.	IPP15 in 1995 in Tokyo Robert created the Dovetail and a Half (triangle) and Norman created the Corollary Dovetail. I have neither.	IPP16, 1996, Luxembourg Robert submitted the Dovetail Donut. Norman submitted the Spider's Secret Box, which was licensed by Bits & Pieces. (It is not a dovetail puzzle.)
IPP17 in 1997 in San Francisco CA Robert created the Bolted Dovetail. Norman created the Dove Tangle.	IPP18, 1998, Tokyo Robert's Fat and Thin Triple Dovetail Norman created Pharaoh's Secret which I don't have.	IPP19, 1999, Heathrow, England Norman's L-Bow Dovetail Robert submitted the Cutaway Double Dovetail (also L shaped) which I don't have.
IPP20, 2000, Los Angeles CA Robert's Dovetail Burr Norman's DoveTail Bar I have neither. IPP21, 2001, Tokyo - No new puzzles from either.	IPP22, 2002, Antwerp Belgium Robert's Dovetail Pepper Shaker, and Norman's Dovetail Salt Shaker. They only work as a set - tools from one are needed to disassemble the other. My second Sandfield puzzle(s), obtained from Norman.	IPP23, 2003, Chicago Norman's Dovetail Cherry Surprise Cake Robert submitted the Dovetail Jewel Box, which I do not have.

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The 2003 puzzles were the last to be crafted for the Sandfields by Perry McDaniel. However, Perry is still making fine wood puzzles. This is Perry's Marbled Walnut Sheet Cake box from 2006.

Whether you refer to them as Puzzle Boxes, Trick Boxes, or Secret Boxes, the idea is the same - a container with no obvious way to open the lid. Japanese craftsmen have a long history of producing secret opening boxes, requiring many steps to open, and finished in a characteristic style of woodwork. More recently, several other foreign and domestic artists have been producing new varieties of puzzle box.

I am very pleased to own one of Kagen Schaefer's Rune Box puzzles, number 7 of 30. It's five inches on an edge and made of Cocobolo, Maple, and Ebony. For more info, see Kagen's website. Kagen is also an honorary member of the Karakuri Creation Group.

Six interchangeable cocobolo and maple sides ride in grooves in a precisely fashioned ebony frame. A clever system of orthogonal dovetails mates the cocobolo exterior panels to their maple interior portions and allows each side to move in specific ways. Each side shows a "rune" symbol providing a clue to its allowed motions. The sides obstruct each other depending on their positions. By moving each side in its four possible directions, you're navigating a maze. Your objective is to move one side so it exits the maze (can you guess which rune labels this side?), thus unlocking the box and permitting a side to be completely removed. All sides can then be removed, and re-arranged to provide a new (and potentially more difficult) challenge.

This is Immaginario Lunare by Franco Rocco. I purchased mine from James Dalgety.

A pear-wood hollow sphere somewhat over six inches in outside diameter and divided into 8 sections is held together by an intricate system of grooves and pins. The sections must be manipulated in sequence to open the puzzle and disassemble it. The puzzle is accompanied by a folio of instructions and diagrams on loose pages. Mystical symbols engraved on some of the octants may be of help...

The hardware and associated sockets in the wooden pieces have subtle differences and must be carefully matched to achieve the proper clearances and tolerances. I have found that certain necessary moves become impossible if the wrong elements are combined during re-assembly; then the puzzle must be dis-assembled and reconstructed again.

The fanciest box in my collection is this Stickman Box No. 5, multiple 18 of 45, designed by Robert Yarger and purchased at Cubic Dissection. What begins in the workshop as 15 pounds of maple, walnut, cherry, bloodwood, and oak, ends up as over 75 intricately shaped pieces that weigh in toto a mere 4 pounds and hold together without glue or fasteners! Overall, the box measures 10.5" x 6 3/8" x 5.25". The box can be opened in 32 moves, and then disassembled to its constituent pieces, if one is brave and/or foolhardy enough!

I also acquired a Stickman Box No. 3: 

and a tiny Stickman "Snowflake" box No. 9:

At IPP26 I bought a Stickman #11 Fulcrum Box.

See my magnetic puzzles section for a Stickman #13 Chopstick Box.

See James Strayer's website for a full collection of Yarger's boxes.

The Karakuri Creation Group is an association of Japanese craftsmen working to popularize and preserve the tradition of fine Japanese woodworking and Puzzle Box techniques, as well as extend it in novel directions. They run a club which for a nominal annual fee entitles members to several beautiful puzzle catalogues and books, one or more Christmas gifts, allows members to purchase their products at a discount, and provides access to private areas of their website.

Hermit Crab Box by Shiro Tajima I have the dark walnut version.		Here is a Walk of the Ladybug by Tatuo Miyamoto of the Karakuri Creation Group. This is a beautiful box with a whimsical mechanism. I had trouble with the drawer at one point, probably due to humidity, but with the cooler, dryer fall weather the mechanism once again works properly.
Karakuri Small Boxes (Kobako) Nos. 1, 2, 3, 4, 5, 6, and 7. Each has a different trick.
The Karakuri Club Christmas 2005 Gifts (4 of 8)
Cube Box by Akio Kamei		Free Dial by Shiro Tajima
Secret Star by Hiroyuki Oka		Contrary Card Case by Tatuo Miyamoto
If you don't care about ruining the fun of opening them yourself, click the button to show them opened (and refresh the page to close them again):  Open the boxes! No, really!
The Karakuri Club Christmas 2006 Gifts (4 of 8)
Covered Chimney by Hiroshi Iwahara		Soba Box by Hideto Satou
Trick Box with a Top by Yoshiyuki Ninomiya		Spring Box by Akio Kamei
Open 'em!
The Karakuri Club Christmas 2007 Gifts (4 of 9)
Secret Base by Hiroshi Iwahara		Hinge by Tatsuo Miyamoto
Covered Type Secret Box by Yoshiyuki Ninomiya		String Box II by Akio Kamei
Open 'em!

I have some inexpensive traditional Japanese trick boxes, purchased at a shop in Hakone. You can read an article by Jerry Slocum discussing Japanese Puzzle Boxes and showing a diagram of the typical solution pattern.
	This miniature (mame) box works well.	Here is a trick cigarette case.
These two Japanese secret-opening boxes were made by Hiroyuki Oka and purchased from The Unique Box Shop.
This is a 5 sun, 9-step box called "Notch Stripes."	This is a 3 sun, 12-step box. The different woods are: White - Mizuki wood from Japan, Yellow - Inomi wood from Japan, Green - Hoo wood from Japan, Beige - Beech wood from Germany, Brown - Walnut wood from North America, Red - Hekakoro Rengasu wood from Southeast Asia

Puzzle boxes have been around for a while. "Turned" specimens (as in made on a lathe; also known in the U.K. as "Treen" - made from wood) were produced in the 1800's. This is a Castle Money Box, very similar to the one shown in Hoffmann's Puzzles Old & New on page 22.

The puzzle is a nice size, larger than I expected, and the wood (I believe it is Boxwood) has a warm, beautiful glow.

This is another vintage Boxwood piece - the Dice Box (or Barrel) described in Hoffmann.

Here is another antique "treen" piece, the Ebony Puzzle Ball described in Hoffmann. The circular engravings are supposed to disguise the opening.

This is the Apple Puzzle from woodturner John Berkeley. The Apple won an Honorable Mention in the IPP21 Design Competition. John also offers reproductions of many of the classic turned puzzles in Hoffmann.

The simplest trick-opening box has to be the two-piece Black Box. I got mine a long time ago, but supposedly Mag-Nif or Oriental Trading Company offers them.	This "Treasure Box" is another classic design in plastic. It is similar to the Black Box in that everything depends on your grip. U.S. Patent 5611536 - Foreshew 1997	2-drawer Trick Box
The Snap Box from B&P	The Corian Slider Box from B&P - designed by Frank Chambers	The Constantin Knob Box from B&P
The Secret Sliding Box from B&P	My friend Jay gave me a beautiful Burl Box. It is more art than puzzle.	I bought a hummingbird box when I was in Costa Rica. They're hand-made, but mass-produced for the tourists. Not very puzzling.
This is the Black Box designed by W.L. van der Poel. Peter Knoppers has some info on his site. It is discussed in CFF, issue 25, part 3, December 1990, pp 4-7.	Secret Rectangle Box B & P	Boardman Box B & P
	Keeper Box B & P	Alice's Puzzlement From Pentangle.
Snap Latch box - Bits and Pieces	Eclipse box - Bits and Pieces	The rather controversially named "Bin Laden" box (laden means drawers in Dutch) - the name is meant as a hint to the solution. By Rik van Grol, IPP26.

The Haselgrove Box requires you to tilt it this way and that, in an effort to reposition internal sliding blocks and allow the pieces to be unlocked and removed. Then you must re-assemble it. I have a version from Cleverwood, and a very nice version from Eric Fuller made from Wenge and Purpleheart.
Eric also made this never-before-produced design called Meijer's Box, from Maple and Spalted Yellowheart. According to Eric, Berend Meijer "became fascinated with the Hazelgrove box and decided to make his own design along the same lines. His unique creation uses a sliding piece that moves into a hole in the front of the box to lock the pieces in. The concept is the same as the Hazelgrove box, but the operation is completely different and quite tricky."