My rough inspiration came from "Young Mad Scientist's First Alphabet Blocks" by Xylocopa http://www.xylocopa.com/product/mad-science-alphabet-blocks. As a science teacher I still plan on making a more science based set one day, but my graphic design skills need work.
Step 1: Designing the Blocks
In the computer program Paint, create a template of large boxes for the letters etc. to go into. Two of the sides will be light (unburned) images on a dark background and two sides will be dark images on an unburned background with a dark border. Using copy and paste I created a 5 by 6 block pattern with equal spacing horizontally and vertically to allow for the edges of the blocks to eventually be rounded.
The actual size of the boxes is not important at this point. More important is getting maximum detail without getting pixilated.
With the templates created, copy and paste images to fit in each box, saving the files as separate versions. I used:
Side 1- Dark box with light capital letters (A-Z plus additional A)
Side 2- Light box with dark numbers (two sets of 0-9 plus basic operations)
Side 3- Dark box with light lower case letters
Side 4- Image relating to each letter. I used superheroes and cartoon characters. Maybe sports teams? Animals? Food?
Note: The hardest part of this project was finding or creating and then manipulating appropriate images. Ideally they need to be only black and white so that the burning process is an all or nothing operation instead of shading. Original artwork is preferred as it avoids any potential copyright issues.
Step 2: Making the Blank Cubes
I cut the 2x4 into 1.5 by 1.5 by 1.5 cubes using a table saw for the long cuts followed by a mitre saw for the cross cuts. At this point sand the sides of each block but not the edges or corners.
Step 3: Burning Pt. One
Lay the blocks in the laser bed with end grain running in the same direction with no space between blocks. Double and triple check the size and starting position of the image to be burned to ensure the blocks are lined up straight and each block will have its image relatively centred.
By rotating each row of blocks 90 degrees after each pass, the four traditional sides can be engraved. Don't shuffle up the blocks and the 4 images will relate to each block (B, 2, b, Batman all on the same block etc.)
Step 4: Burning Pt. Two: Puzzle Sides
Side One- Name, designed and sized in Microsoft Word
Side Two- Skeleton (both parents are in healthcare)
Instead of being careful not the shuffle the cubes, I intentionally mixed them up before laying them on the laser bed to make for a more interesting puzzle.
Again double and triple check the position of the laser before beginning.
Step 5: Finishing
If desired, butcher block oil (food safe mineral oil) can be applied at this point to prevent staining or water damage.