Wooden Puzzle: Six Blocks in a Box

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About: I got an old sewing machine when I was just a kid, and I've been hooked on making stuff ever since. My name is Sam and I'm a community manager here at Instructables.

Intro: Wooden Puzzle: Six Blocks in a Box

This is an incredibly easy-to-make wooden puzzle that can be completed with minimal woodworking tools. No 3D printer, laser cutter, or CNC machine needed!

The puzzle consists of six equally-sized half-cube blocks that fit into a box in only one way. It's simple, but deceptive enough to entertain people for a while until they figure it out. 

This is not an original idea of mine. It is based on a puzzle I saw at the Pacific Science Center in downtown Seattle, and I thought it would be fun to duplicate it. 

This is a quick project that can be done is just a few hours. Take a look, and then go make one for yourself!

Step 1: The Solution

It seems against the whole point of a puzzle to give away the solution up front like this. But in order to make it, you need to know how it goes together.

So here it is. Trust me, it's not as easy as it looks!

Step 2: Make the Blocks

I used some 4" by 4" wood out of my scrap bin to make my blocks.

The actual width of the sides of 4" by 4" boards is 3 1/2", so I needed to cut pieces that were 1 3/4" tall to get the desired half-cube shape.

I set up a stop on my miter saw and cut six pieces. 

Another simple option would be to use pieces of 2x4 studs. Since they're actually 3 1/2" by 1 1/2", you would need to first trim the width of the board down to 3", and then simply cut off six square blocks.

Step 3: Measure for Box Opening

The size of the blocks you make will dictate the size of the box you need to make to put them in.

The box should provide just enough wiggle room that the blocks can be removed easily. I'd suggest making a box with an opening 1/8" to 1/4" over the size of the blocks when stacked in the completed puzzle configuration, like in this photo.

In other words, the height, width, and depth measurement of the box opening should be just a little over 1.5 times the length of one block.

For me, that meant making a box with an opening that was 5 3/8" all around.

Step 4: Make Box

I made my box out of 3/4" pine boards. Not including the lid, the sides of the completed box are 6 7/8" wide, and 6 1/4" tall. (So two sides were cut 6 7/8" by 6 1/4", and two sides were cut 5 3/8" by 6 1/4".)

The bottom piece is 5 3/8" square, and the lid is 6 7/8" square.

I assembled my box with glue and brads. A simple box like this can be assembled with just glue, or with nails or screws. If you use screws, be sure to pre-drill your holes so the wood doesn't split.

Step 5: Touch Ups

I filled all the brad holes in my box with wood filler and sanded everything smooth to prepare for painting.

If you have access to a router table you can use it to round over the edges of the blocks as I have done. If not, just sand all the sharp edges off the blocks by hand or with a power sander.

Step 6: Finishing

You could use stain, paint, wax, or whatever you like to finish the box and blocks.

I stained my blocks with oil stain and then sealed them with shellac. When the shellac was dry, I gave them a light sanding and then applied some paste wax.

For the box, the inside was finished basically the same way as the blocks. For the outside I used spray paint, shellac, stain and wax to get the look you see. I was experimenting with different things and the finished look of my box was mostly an accident, but I like the way it turned out.

There are so many routes you can go with wood finishing, and everyone has their opinions on the matter. Sometimes it's fun to just experiment and see what happens. Make sure to have adequate ventilation!

Step 7: Hardware

I used some old hinges to secure the lid to the box.

You could add handles and a clasp of some kind at this point, but I chose not to.

I originally planned on putting little rope handles on mine, and had drilled holes in the sides to put them on. But I ended up not liking the way they looked and decided they weren't really needed anyway, so I took them out. The holes were plugged with dowels that were then stained (second photo). Now they just add a little character, which is nice.

Step 8: Final Thoughts

A small problem with this puzzle is that in storage, it gives itself away.

So if you have a visitor over and they ask "Hey, what's in the box?", don't say "It's a puzzle," until you've dumped the pieces out. If they open it up knowing it's a puzzle they'll pay attention to how the blocks are oriented!

Well, that's it. Thanks for taking a look.

If you make one, post a photo in the comments. I'd love to see it!

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15 Discussions

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mrsmerwin

1 year ago

I have a copy of this puzzle and I still want to make one.

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darbinorvar

3 years ago on Step 8

Looks awesome Sam! I love the project and the effect of the paint.

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wzeller

4 years ago on Introduction

I was turning this over in my head, thinking over how I'd go about all the steps. I thought about cutting the blocks from a 2x4, routing the corners to round them, then sanding them, then varnishing them, and then realized that the result would be exactly like by son's building blocks. Those classic wood blocks every kid has include a 2x4x4 size. I checked, and sure enough he has more than six of them. Now all I need is a box! First example I found via Google search, for illustrative purposes: http://www.globalindustrial.com/p/office/school-furniture/junenile-furniture/toddler-blocks-twelve-shapes-36-pieces

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jjoy10

4 years ago on Introduction

Seems it looks easy, the only thing we should cut the wooden blocks in right size. Otherwise it wont be fitted inside the box.

http://www.ajstechnoflow.com/

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syrrus

Reply 4 years ago on Introduction

I wish I could upvote this comment. You're my hero.

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perryb

Reply 4 years ago on Introduction

First off, that's the best reply on Instructables. Secondly, I always watch this site for easy, interesting and cheap projects I can do with our Church-run boys club. I have a huge amount of salvaged skid wood, so this will cost me a pair of hinges per boy only. Thanks!

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jbrecken

4 years ago on Introduction

I have the plastic version of this, (available here: http://www.thinkfun.com/packitin ) and they also include the three small cubes that take up the rest of the space in the box. I'm not sure if it would make the puzzle easier or harder to solve if your wooden version added those. It might be as easy as cutting a seventh slice and then dividing it into quarters.

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seamsterjbrecken

Reply 4 years ago on Introduction

Well look at that! I think it's interesting that they include the three small cubes.

I really deliberated about making some as part of the puzzle to fill the voids, but ultimately decided against it. My conclusion was that it would make the puzzle easier solve.

My logic is that the voids offer a little bit of necessary subconscious confusion--it seems counter-intuitive that in order to successfully fill the box, you have to leave some empty space. Anyway, great comment. Thank you for sharing that link.