The Eggyrint

In one of our recent Instructable, we presented a program to generate 3D printable realistic bird eggs models that can be used for teaching and crafting.

We desired to explore the possibility of using these egg forms to build other egg-shaped devices. After brainstorming with my son Leonardo, we came out with the idea of a puzzle. It is common to find a plastic puzzle labyrinth inside chocolate eggs at Easter time as a surprise, but what if the puzzle becomes the egg itself? From this basic idea sprang the Eggyrint: a 3D maze embedded in an egg form. First, we designed a conceptual prototype of three relatively small mazes. Then, we integrated them into an egg form generated using our program to make a new toy that is entertaining, challenging, and innovative. In this Instructable, we will explain how to 3D print and assemble this prototype of Eggyrint.

• A slicer program. We have used Ultimaker Cura for this project, but you can use any other slicers.
• A 3D printer. We have used the Wanhao duplicator i3.
• Sandpaper, sandstone, craft knife and pliers to clean 3D-printed parts.
• Screwdriver with hex bits.
• Double-sided tape and scissors.
• Superglue.
• Steel balls of 1-2 mm diameter. They can be recovered from a small bearing used, for example, in an old fidget spinner.
• Painting for the final decoration (optional).

The Eggyrint is a challenging 3D puzzle involving getting a metallic sphere from top to bottom of an Egg-shaped toy by solving three internal stacked 2D mazes connected by vertical shafts. All the parts composing the Eggrint, shown in the Figure, are 3D printed. The three mazes (Maze A1-C1) are composed of upper and bottom parts that facilitate printing. On the external surfaces, four pegs allowing to connect to be connected to the elements of the eggs. Middle and bottom mazes are more extensive and, thus, more challenging.

Between these puzzles are plastic connecting parts (A-D) with vertical shafts that connect the mazes to allow the steel ball to move from one maze to the next. Finally, a cup and story feet are used to enclose the metal ball into the device and to help it keep standing when it is not used.

Of course, having a puzzle game like the Eggyrint means you cannot see the puzzle, only the Egg it forms. The device is modular to make possible the 3D printing and to help you retrieve the ball if you get stuck (this may be what you have to do for quite a few turns). More importantly, this modularity allows you to change mazes rings with new ones, extending the game's fun.

All the STL files of the device, named as in the Figure in Step1, are attached. Download it and use the slicer to prepare the files with gcode instructions for the 3D printer.

MAZE parts

We have printed the mazes (A1-C1) with a layer resolution of 0.2 mm, infill 20% and full printing supports. We have used coloured PLA for this project, but a transparent one could be better if you get stuck solving the puzzle, as it would allow seeing the sphere's position more quickly.

Print the two halves of the mazes with the maze facing up. This way, the labyrinth paths will be printed clean and smooth. After printing, remove the supporting material and smooth the surfaces using sandpaper to improve the contact with the other parts. Use a hex bit of appropriate size screwdriver, clean the maze's paths and the entrance and exit holes. Try the maze with a steel ball. Finally, connect the two halves of the maze faces using the two pegs on the faces using the super glue to stick together firmly (make sure that the glue is not blocking the paths!).

CONNECTING PARTS

For Parts A-D, cap and support feet, we have used 0.3 mm with acceptable results for a prototype version, but a smaller resolution will give better results. After printing, use a screwdriver or a drill point of appropriate size to free enlarge and free the connecting shaft.

ASSEMBLY

Connect the part with the mazes in the sequence given in Figure Step 1. Make sure that the exit hole of one of the mazes connects with the entrance of the next one! I suggest marking the part and the maze with a marker to ensure the correct connectivity. Only one of the four connecting shafts will be used in this prototype. Double-sided tape can firm the connection between the mazes and the other part. Do not glue as the purpose of the parts A-D are the interchangeability of different mazes. Add the support feet and, from the top, the steel ball.

Maybe try to decorate the egg using acrylic markers or paint and with maybe more artistic skills than us!

And that is all. The Eggyrint is an interchangeable, printable 3D puzzle for a new form of entertainment. Currently, as a prototype, we have created only two versions of the mazes. The second maze set is attached, giving you eight possible games using the combinations of the two pairs of 3 different mazes. However, adding up to four maze pairs (as the current number of shafts), it would be possible to have up to 64 3D maze games.

So, try to make one and have fun!