Captive Ring Puzzle




Introduction: Captive Ring Puzzle

About: My name is Troy. I'm a Mechatronics graduate studying Mechanical Engineering. I like to make things and spend time outdoors (especially SCUBA diving). I am a Community Manager for Instructables.

I love puzzles. Not jigsaw puzzles where you assemble a box of oddly shaped pieces, but objects that make you think. Objects that make you look at everything from a different perspective, that make you understand the world isn't always as it seems. These are the puzzles I love.

I first saw this puzzle posted by pocket83 and knew I needed to make my own.

This simple puzzle is made of metal, brass, and wood. The ends are not removable, the ring doesn't come apart, there is no optical illusion present, nor is the image changed to deceive.

With a handful of tools and some scrap wood, you can make this simple puzzle to amaze your friends and family.

Step 1: Tools and Materials

There are a few things you will need to make this puzzle.


  • Saw
  • Drill Press - preferred (a hand held drill could also be used)
  • 1/4 inch drill bit
  • Compass
  • Awl
  • Disk Sander, Palm Sander, or Sanding Blocks
  • Hacksaw or Angle Grinder


Step 2: Cut Wooden Discs

Cut two wooden squares that measure 2 3/4 x 2 3/4 inches (and about a half inch thick). I used a crosscut sled on the table saw. Using an awl or nail, mark the center of each block and draw a circle with radius 1 5/16 inches using a compass. Using a band saw or similar saw, cut out the circle just bigger than the mark made by the compass. Make the discs perfectly round by removing the excess material with a disk or belt sander.

Step 3: Drill Three Support Holes

Using the compass, draw a new circle with radius 1 1/32 inches and divide that circle up evenly with the compass. This can be done by keeping the compass at the same radius as the circle, select a point on the circle and mark the radius away from that point. Transferring the "center" of the compass to these new marks and marking the radius again will result in the circle being divided into roughly six sections. Select and mark three of these divisions.

Drill out the holes as deep as possible without drilling completely through the wood.

I wanted the grain of the two discs to go in the same direction, so I took special care to mark the points of the second disk so this would happen.

Step 4: Polish the Rod

Take a 10 inch section of rod and insert it into a drill. Starting with 220 grit and ending with 600 grit sand paper, sand the rod till it's as shiny as you'd like. You can even use buffing compound if it's available to make the rod really shine.

Step 5: Cut Rod

Using a hacksaw or angle grinder, cut the rod so you have three pieces 2 inches long, and one 1 3/4 inches (this center rod will be too long and will need to be cut to final length later on). Using a bench grinder or disc sander, remove the burs caused by cutting the rod.

Step 6: Drill Center Holes

The center holes are the core of this puzzle. Drill one hole deep enough to recess the magnet about 1/16 of an inch. This will be what holds the center post in place making it appear solid. Drill the other center hole as deep as possible without drilling completely through the wood. Then take a 1/4 inch straight router bit to flatten out the bottom of this hole. This will allow the center rod to slide as far as possible, and give clearance for the brass ring.

Step 7: Test Fit

Test fit everything. Make sure everything fits together and that the center rod gives enough clearance for the brass ring to be replaced. If there isn't enough clearance, carefully trim the center rod shorter until there is enough space for the ring to slide in and out.

Step 8: Chamfer Edge

Using a router, add a small chamfer to the edges of each disc. You could place any edging you like on the disk to suit your personal taste.

Step 9: Sand

Using a palm sander or sanding blocks, remove all rough edges and markings from the design layout process.

Step 10: Apply Finish

Insert nails through some scrap cardboard to support the pieces to be finished. Using fine sandpaper to clean up irregularities in the finish between coats, apply four or five coats of lacquer.

Step 11: Cut Notches in Outside Posts

Using a hacksaw or thin disk angle grinder, cut notches for the epoxy to hold onto the rods in the next step.

Step 12: Final Assembly

Using quick set epoxy, embed the magnet into its corresponding hole. Allow this to dry for a few hours to ensure the movable center rod will not pull it out of place when finishing the assembly (speaking from experience, trying to reattach the magnet after it has fallen out is nearly impossible to do without ruining the rest of the puzzle). Apply epoxy to each of the posts and ensure everything is square. Let sit for 24 hours.

Step 13: How It Works

If you haven't figured out how it works by now, it's deceptively simple. The center post slides down when pulled from the magnet. This allows the ring to slip over the top of the post.

If you happen to make one or something similar, please leave a comment showing your favorite puzzles.

2 People Made This Project!


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22 Discussions


1 year ago

Great instructable. Well done for the way you have stepped through each individual stage of construction. Will look forward to making this one for my neice.

I love it. One of the BEST and with pictures. Kudos.


1 year ago

Good idea and good instuctions! Great stocking stuffer idea!

So well done and thorough... Looking forward to make the same. Would the stainless steel bar be better since more corrosion resist?

Will put the giant sized Lord of the ring, it needs to be locked up :)

1 reply

Hi, unfortunately you couldn't use stainless (or brass) for the centre pin as it isn't magnetic. Perhaps you could use a varnish or lacquer? Good luck.

This is very creative. I like it

Great Idea. I love little portable puzzles like that. Awesome job!


1 year ago

You provided the solution to "what can I make for the grandchildren this year?" THANKS! Neat puzzle. So I made a dozen. I did use a shortcut that may be of interest to those making multiple copies. I used a hole saw in my drill press. Once the saw had cut about an 1/8" and the pilot hole had not gone all the way through, I removed the pilot drill (i.e. the 1/4" twist drill). clamped the workpiece in place and completed the cut with the hole saw. Then I sanded the edges by mounting the blank discs in the lathe and sanding as the disk rotated fairly slowly.

You might also be interested in the note I attached to each gift puzzle:

year I decided to make a simple little curio for a few friends —something
totally useless, just a novelty with a brass ring secured by steel posts
between wood caps.

hardwood lumber is becoming very expensive and there is a growing market in
reclaimed woods. I went on line
and ordered several pieces of oak and maple. Responsible dealers always share the origin of the materials
they sell. Imagine my surprise
when the beautiful pieces I ordered came with a tag stating that the wood had
come from “shipping coffins” which had been stored in a New York City warehouse
for many years.

more detail than I wanted to know, I learned that the wood used in these curios
had been a coffin in which Eric Weisz’s body had been shipped from Detroit, where
he died to New York City on October 27, 1926. (He is now interred
in the Machpeiah, a Jewish Cemetery in Queens.)

wondered why, in making your gift I had such a hard time keeping the ring in

it be because the wood in your gift had once transported the body of Eric
Weisz, born in Budapest, Hungary on March 24, 1874. The same Eric Weisz the world came to know as Harry Houdini?


1 year ago

Nice! I gotta try this one! One thought about cutting the discs; I plan to select a hole saw with in ID of the proper disc size, cut a hole in a scrap piece of ply, then clamp the hardwood to the piece of plywood, remove the center drill bit from the hole saw, cut the hardwood to form one of the discs through the hole I just cut in the ply, reclamp and cut a second disc. That should save time in making the two pieces the same size and "perfectly" round.

Thanks for the link and the heads up; I have added this to my "TO DO" list, right now with X-mas around the corner I'm finishing a work desk for my grandchildren (Rustic-Modern) style, so right after the holidays I have a new "Trick/Puzzle" to work on.

Compaq1501, your comment is a puzzle.

tomatoxkins: I was studying the photos, thinking the straight rods were brass. Then it hit me. They had to be magnetic, therefore they could not be brass. Some stainless steel is magnetic and could be used. Not all is though, and it could not be used. Great instructable.

Thanks for all the detail, now I can build one for my daughter

You have to puzzle out the "trick," so that makes it a puzzle. Reminds me of a Superman Comic book I read in either the late 50's or early 60's. An alien race is testing Superman (the reason I don't remember, could have been to see if the human race would be destroyed or not...) and they put him in a small iron bar cell with a locking door. He is told he can't use his powers to break out, and there are no trick openings. They put the key in the lock and turn it, and remove the key. He must figure out how to get out to prove he is intelligent. This is in the same vein.

Hello: It's always amazing to read "critics" who obviously only have the talent to shoot off their mouths & not TRY to use their "FREE THINKING BRAIN"; Trick or puzzle, it's very entertaining, simple in all elements and looks easy to build. Finding the metal ring and similar thickness rods might be a chore; however, it's a good challenge.

Finding the ring

Really clearly explained, thanks. I'm going to make this, all being well...

I'm not sure which part of the 'We have a nice comment policy' isn't clear to some of the people who have commented on this excellent instructable.


1 year ago

Wow aren't you the clever one. Trick, puzzle whatever, a great instructable with excellent detailed step-by-step guide.

1 reply

yeah its a great write up. very detailed, and im sure it'll help people build it. I just think it should be labeled differently... no need to get upset

the real benefit to this instructable (which is excellently written and laid out) is in the tricks used to build the device, to apply to other projects/situations

If someone was looking for a true puzzle they'd have wasted some time reading through every step to find in the near to last instruction that the "puzzle" solution is to essentially cheat

Well done! I agree with people who are commenting that it is a trick and not a puzzle but really, that doesn't matter. Its an excellent 'ible, well laid out and clever. Thanks! BTW... just as a warning... using a router with a small round disk is pretty risky. Perhaps come up with a jig using the holes to stabilize the disk and stop it from spinning by accident?

My grandson would love this.