Box Puzzle

This project is both a puzzle and a wood working project.

The puzzle is made up of 13 small wood blocks assembled on a wood tray. The challenge is removing the blocks from the tray, mixing them up, and then “simply” putting them back where you found them. It can be extremely difficult to solve or less challenging depending on how you choose to set it up. The options will be discussed as we go through the construction.

The woodworking part shown here is the most basic form of box construction. Those that have the skill and equipment can make this project a little better finished piece of woodworking using dovetail joints, finger joints, exotic wood, etc.

All of the puzzle blocks are a different size. Therefore there is only one solution for placing the blocks in their correct location. There is no attempt to show how to solve the puzzle because it is primarily a trial and error process.

Step 1: Let's Get Started...

Materials required:

1. 3/8” Wood board – one 24” piece x 5 ½” will be more than enough.

Note: you could use ½” stock instead of 3/8”. The ½” stock is available in hobby stores and home improvement centers. I didn’t use ½” because it only was available in Poplar and I didn’t care for the green color. All of the box dimensions are based on using the 3/8” stock so adjust them if you choose the ½” option. As long as I had to rip or plane the wood to size anyway I decided on 3/8” to make the project as small as possible.

2. ½” Wood board – one 6” x 3” piece.

3. ¼” Wood board – one 12” piece x 3 ½”.

4. Small piece of ½” wood dowel

5. Wood glue

Tools required:

1. Band saw and/or Table saw

2. ½” Electric drill

3. Sand paper

Because of the variations in the thickness of wood available and wood cuts, we’ll use the following building sequence.

1. The tray will be made first. The tray bottom is the only piece in the project cut to an exact size.

2. The next step is to fit the tray “rails” to fit the tray bottom.

3. To finish the tray we’ll add a pull knob and install the tray front.

4. Once the tray is complete, we’ll make the box to fit the tray.

5. The last step is to cut the puzzle blocks to fit the tray.

Step 2: Tray

The tray bottom is 6 ¼” x 3 ½”, made from the ¼” stock. Remember this part is the only part that is cut to exact dimensions. After you cut it, make sure all four corners are square.

Step 3: Tray Railings

We need a small railing on the tray to keep the puzzle blocks in place. The railings are made from 1/4" x 1/4" strips.

We need three ¼” x ¼” x 6 ¼” strips for the tray railing. As long as you are set up anyway, cut five of them. Two will be used a little later in the box for tray guides.

Cut and miter the three railings as shown. Two of them will be 6 1/4" long and one will be 3 1/2" long. Set the railings on the tray base and test for a perfect fit. Glue them in place.

Step 4: Tray Front

The tray front is made from 3/8" stock, 3 1/2" x 7/8".

The tray front has to fit flush with the front of the box. Therefore it has to fit inside the box. It will be attached to the tray so it has to be able to move in and out the box without restriction. To allow that to happen the tray front has to be slightly lower than the top of the box. Sand/shave ~1/32” off the top of the tray front.

We have to add a pull knob to the front of the tray so we can pull it out of the box.

Note: There are a many wood knobs available at home improvement centers if you would rather go that route.

The knob is made from ½” wood dowel.

a. Make a mark ½” from the end of the dowel.

b. Cut off ~3” of the wood dowel.

c. Insert the dowel into a ½” drill. Spin the edge of the dowel against a sander or piece of sand paper to create a rounded edge.

d. Cut the knob at the 1/2" mark. Sand the flat surface of the knob so it fits tight against the tray front.

e. Mark the center of the tray front for the knob.

f. Glue the knob on to the tray front.

Step 5: Glue the Tray Front to the Front of the Tray

Set the tray front tight against the front of the tray. It should be a tight flush fit. You may have to sand the front of the tray to get the railings and tray base to form a smooth surface.

After the tray front is attached, sand both sides and the back of the tray.

Step 6: Building the Box

We'll start with cutting the box sides and box end. The box sides and box end are made from 3/8" stock. The box sides initially are cut 7 1/2" x 7/8". They will be trimmed to size later.

The box end is 3 1/2" x 7/8". Add ~1/16” to the length. It will be trimmed as needed in the next step. The tray is 3 ½” wide so the box has to be slightly wider to allow the tray to slide in and out of the box without binding.

Step 7: Set the Box Length and Width

Set the box end flush against the tray end. Measure the length between the back side of the box end and the front side of the tray front. That will be the length of the box.

Place the box end in between the two sides. The box sides should be tight against the box end.

We need about 1/32” gap on both sides of the tray to allow it to easily slide between the box sides. Remember we added 1/16" to the length of the box end. Trim the length of the box end as needed. Note that the two sides will fit tight against the box end but the tray front needs to have the same 1/32" gap as the tray. Therefore the actual width of the box should be measured from the back end of the box.

Step 8: Box Top and Bottom

We now know the exact box length and width so we can cut the box top and bottom. The box top and bottom are cut from 3/8” stock. As a rough guideline the size for each piece should be about 7” x 4 5/16”.

Step 9: Begin the Box Assembly

Set the box sides and back in place on the box bottom. Set the tray in place with the tray front flush with the front edge of the box bottom. Make whatever modifications are necessary so both side pieces and the back piece are flush with the edges of the box bottom and the tray front is flush with the front of the box.

Step 10: Align Tray With the Box Top

With the tray in place, temporarily place the box top in place. Check to make sure there is a small gap between the top and the top of the tray front to allow the tray front to slide out. If there is no gap, sand down the top of the tray front. The tray front should fit flush with the front of the box. Do NOT glue the top in place yet.

Step 11: Install Tray Guides

We need to make some tray guides to keep the tray from flopping up and down and possibly dislodging some of the blocks. If a block gets hung up you won’t be able to pull the tray out and your project could end up as firewood. We also don’t want the top of the puzzle blocks rubbing against the box top.

The tray guides are made from ¼” x ¼” strips that were made previously. Cut the tray guides to 5 ½”.

Round off one edge on one end of each tray guide. Making the guides shorter than the length of the box and rounded will make it easier to insert the tray.

The tray guides will be placed flush back against the back of the box and top edge of the box sides. Place one tray guide in place as shown. There should be less than1/8” between the tray guide and the tray rail.

Glue both tray guides in to place.

After the glue dries, sand the entire top surface to allow a tight fit for the box top.

Step 12: Install the Box Top

Insert the tray one more time. Temporarily place the top in place. The top should fit tight on all three sides. The tray front should be flush with the front of the box. Press down on the box top and slide the tray in and out. If everything looks and works ok, you are ready to glue on the box top.

Glue the top in place.

Step 13: Final Box Cosmetics

We need to add a little cosmetics to the box. It will not only make it look like a finished project but to help prevent someone from opening the box upside down and spilling the puzzle blocks.

a. Make sure all four side sides, top, and bottom are sanded smooth.

b. Round all four corners of the box. You could just sand them if a router is not available.

c. Round all four sides of the top. If a router is not available you could also use a partial miter on a table saw cut for the top piece edges.

Step 14: Puzzle Main Block

The puzzle main block should be 6” x 3”. Mark and cut the Puzzle main block from the ½” stock. You can use the dimensions shown or measure the exact inside dimensions of your finished tray.

I would suggest adding about 1/8” to the dimensions to allow for the blade kerf while cutting the blocks and sanding. In other words, I would suggest making your initial block 6 1/8” x 3 1/8”. Then you can trim the blocks for a more precise fit. Otherwise you may end up with too much space between the blocks. The ~1/8” will not make any significant change to the dimensions of the individual blocks.

Step 15: Making the Puzzle Blocks

Now we can make the individual blocks. There are three rows of blocks and the tray is 3” wide. Therefore the ideal width of each block is slightly less than one inch to give each block a little wiggle room.

Draw the two diagonal lines. Mark the outside perimeter points and connect the lines. Only to satisfy your curiosity, the angle is 60°.

Mark the three blocks in the diagonal area. Note that the dimensions are only given on one side of the diagonal lines. The dimensions on the opposite diagonal are difficult fractions and are not worth the bother. The middle part is not marked and will be whatever is left over. Use a square or a scrap piece cut at 90° to draw the two perpendicular lines to the opposite diagonal.

Mark the two horizontal lines. Draw a mark 1” in from both sides near each end of the block. Connect the lines the full length of the block (excluding diagonal area). The middle row is simply whatever is left over.

Mark all the vertical lines as shown in the photo.

The dimensions for some of the remaining pieces are also not given. Again, those pieces are simply whatever is left over after the other cuts are made.

I need to add a word of caution here before you start cutting the individual blocks. Place each block in the tray as you cut them even though the blocks may not fit exactly into the tray until you finish sanding them. If you just pile them up or happen to drop the whole group, YOU have to solve the puzzle to get them back where they belong.!

Now we can cut all the blocks.

Sand all the edges on each block. Sand a little at a time until you get all the blocks to fit. Slightly sand the tip of the angle cuts to make a more durable edge. Place them back into the tray as you cut them.

You can decide how much space should be between each block. As stated before, this will be the most challenging part of this project. If you have a method to cut the blocks without leaving saw marks you have a huge advantage. Otherwise every time you cut a block you have to anticipate how much extra will be removed when you sand off the saw marks.

To make things more challenging, painting the blocks may increase the size of each block depending on the type of paint used. If that happens to you, sanding is not an option unless you have lots of extra sand paper because your sandpaper will be full of paint. I found it much easier to place the blocks on the band saw with a fence and then just skin off a slight amount along with the paint. Off course then you have to keep in mind you will have to remove even more when you sand off the saw marks.

If you make the blocks a tight fit, you will have trouble manipulating them while solving the puzzle. If you have too much space, it looks sloppy and actually may allow some blocks to dislodge and possibly make it difficult to open the tray.

Fortunately it is relatively easy to mark and cut the puzzle blocks so it doesn't take much to make another complete set. For your piece of mind, I would plan on making them more than once to get it right.

Step 16: Final Touch

You now have to decide how difficult you want to make this puzzle. Here are some options from the most difficult to the least difficult.

1. All blocks cut from same board, wood with no grain showing, no paint, no markings.

2. All blocks painted. Paint all the sides of each block.

3. All blocks painted with some kind of coloring scheme as in the example.

4. All blocks painted. Add a small white dot in the center on the bottom of each block to indicate it is the bottom.

5. Glue the center diagonal block in place somewhat similar to the “Free Space” on a Bingo card.

6. Glue the center diagonal block in place and the four corner blocks.

7. Write a numbering scheme on the bottom of the blocks.

8. Combinations of any of the above.

Whatever difficulty level you choose, take a photo so at least YOU can get it back together

My example for this project used a combination of options 3,4, and 5.

Your block puzzle is now complete!

Step 17: Miscellaneous

1. Apply any stain or paint to the box as desired. You should make that an early decision because you have to decide if you want only the outside or the box interior as well.

2. Exotic woods could be used for the box for natural colors.

3. Give some thought to the colors used on the puzzle blocks. Using the same color for blocks close to the same size will make it more difficult to solve. Using the same colors for each corner block will make solving the puzzle a little easier. The puzzle blocks can also be made out of a variety of wood choices to use the natural colors.

4. Those with the skill and tools can certainly make the box much more attractive using dovetail joints, finger joints, etc.

5. It would be nice to have a way to lock the tray in place. Then it would not fall out or allow someone to pull the tray out when the box is upside down. I just use a rubber band to hold it in place.

I did make a rotating latch in the tray front along with a slot under the top. It worked well but I decided to keep the project as simple as possible.