Jigsaw Puzzle With Secret Code for Escape Rooms

Our family loves puzzles, riddles, brain teasers, trivia, and, of course, escape rooms. Throughout the years, we have created our own escape rooms for the kids' birthday parties and church events. We always like to incorporate a jigsaw puzzle into the escape room at some point. It would usually consists of a 4-digit code printed on cardstock and cut into puzzle pieces. We will hide the pieces around the room, and once the puzzle is put together, the code can be used to open a lock. Not only is this a puzzle idea that we can reuse, but it gives everyone an opportunity to get involved.

Last year, we added a laser engraver to our toolbox, and it has allowed us to take our puzzles to the next level. Our new puzzles are cut from 3mm or 6mm plywood. We utilize a version of the Norton White Tile method to engrave a multiple color image which contains the secret code on the plywood prior to being cut into puzzle pieces. The process works by applying layers of paint (lightest to darkest) to a surface and then using a laser to engrave the inverse of an image. The greater the intensity of the laser the more paint will be removed, exposing the lighter colors. This process is was developed to be used on white ceramic tile but can be easily adapted to wood or canvas.

I used an online jigsaw puzzle generator and xTool Creative Space for the design. 

Tools:

xTool S1 40w Laser Engraver

Software:

xTool Creative Space

Material:

2 - 12" Sheets 3mm basswood plywood

Spray Paint

Clear Coat

CA glue

Combination Lock

I used this online puzzle generator to create the svg file for the puzzle.

 Jigsaw puzzle generator (draradech.github.io)

You can see my settings in the image. The only ones I changed were Corner Radius, Tiles, and Size.

I decided to use a 5x4 piece puzzle. I want it to be challenging but still able to be completed in less than 10 minutes. The size is arbitrary because you will need to resize once you import. 

You will need to decide on the color scheme you want to use. You can keep it simple and stick with black/white or get as elaborate as black/red/orange/yellow/white which is what I will use for our puzzle.

You will begin with a plain sheet of 3mm Basswood plywood. Apply a thin coat of white spray paint and allow to dry for an hour and repeat. I like to apply 2 coats of the white because it will serve as a primer coat. Next, apply an even, thin coat of the yellow spray paint and allow it to dry for a couple of hours before proceeding. Repeat this process progressively working through the remaining colors. (i.e. orange, red, and black). Once complete with painting, allow 12 hours for the plywood to completely dry.

I forgot to get a picture of the red coat, but you will clearly see it in the final product.

I wanted to end up with a puzzle with and overall size of 8”x11.5” including the frame. I imported the puzzle file and resized to approximately 7.5”x11”.

I used the “Outline” tool in Creative Space to create an 0.4” offset and 0.1” inset of the puzzle’s outer rectangle. The inset will be used as a guide for sizing the text for the secret code while the offset rectangle will become the outside of the puzzle, clipping mask, and base layer. 

I imported an image of a paisley background. The color of the image is not critical as long as there are a variety of shades. I liked this image because it had a lot of abstract features and thought it would make an interesting puzzle. 

I added a text for the series of numbers that will become the secret code. I use a grandstander font with approximately 700 ct. You will need to adjust the spacing and proportions for your puzzle using the 0.1" inset line created earlier.

Create a copy of the offset rectangle and use the “Combine” tools in Creative Space to unite it with the secret code. Place this new object over the area of the image that you want to use for the puzzle. With both the vector object and image selected, right click and select “Make clipping mask”. This will clip the portion of the image inside the individual numbers and outside of the rectangle. Since there is nothing to engrave in these areas, it will be skipped during engraving and will keep the top layer color.

Note: When creating a clipping mask, the original image and vector will be deleted. This is why we need to create a copy of our offset rectangle. 

Create a copy of the offset rectangle and moved it to a different layer. This will be used to cut the base layer of plywood.

I used the “Combine” tool in Creative Space to unite the puzzle pieces and frame. Then align the vector to the clipped image. 

Determining your laser settings for the engraving is the trickiest part of the project. There are so many things that will affect how the final result will be and most are out of our control. I have accepted that I will likely need to make 2 or 3 passes to get the desired result. My approach is to run the laser at a high speed (usually 400 m/sec) and adjust my power setting between passes. This process takes a little longer but should keep us from wasting all that time spent painting.

For my first pass, I used a speed of 400 mm/sec and power of 25% and it took approximately 45 minutes. I use a can of compress air to blow off the dust to get a better idea of what my image would look like at this point. I had engraved through the black, exposing the red and was beginning to see some orange. I couldn’t see any of the yellow, so I knew I needed another pass. Keep in mind that the color will change after cleaning and applying a clear coat.

Do not touch the plywood. If it moves at all, you will not be able to do another pass.

My second pass I left the speed the same and reduced the power to 15%. I have a picture where I paused the engraving to show how much more contrast the additional pass will bring out.

After the 2^nd pass, I was satisfied with the amount of yellow that was visible. Also, I could see a little bit of white on one spot that apparently had less paint than the rest of the board. So I decided to stop on this pass.

I use 8 mm/sec and 100% power to cut the puzzle and frame. This is a little higher than I would normally use for 3 mm plywood but I’m not sure how much the paint will affect the laser’s ability to cut through. Since this is a jigsaw puzzle, I want to make sure all the pieces are cut clean.

Use the copy of the outer rectangle that we reserved earlier to cut out a base from the other piece of plywood.

After all the pieces have been cleaned and allowed to dry, use the CA glue to attach the frame to the base.

Assemble the puzzle and apply a clear coat finish. I also sanded the back of each piece to remove any burn marks from the laser.

This puzzle takes my kids about 5 minutes to complete.