If you liked my design, please vote for me in the Papercraft Contest! Every vote is appreciated!
I have been fascinated by a transforming cube that I have had since I was a kid. For those of you not familiar with them, transforming cubes are toys with pictures on the inside that can unfold to reveal different surfaces each time. When the cube is fully unfolded, it creates a cube with a completely different surface than the original. However, this design can be modified so that when the cube is fully folded outward, it makes a completely new shape: a star (check the video above to see how this happens)!
Thus, I set out to create my own variant that could be reproduced from paper, which I titled the Geode Cube, because of its boring exterior color but beautiful internals (just like a real geode). I have also decided to give this template (and the PDO file) for free, and to give a brief walkthrough of how I created the model/template. The final object is a great toy to fidget with, keep on display, or even give as a gift. Made from only 3 sheets of paper, it is cheap to create and can be made by nearly anyone. It also has lots of room for customizability, and you can create it using any kind of paper you like (as long as it's sturdy enough).
The cube itself consists of 8 identical units, which I have called cubies. The cubies are held together by strategically placed strips of paper (I called them bonding strips), which allow the cube to unfold and turn inside out. Each cubie is very easy to assemble, as you will see, and I have provided very detailed instructions and 3D models to help guide you, so don't be shy to attempt this if this project will be your first papercraft!
Now, lets begin making!
For those of you only interested in making the model and not the design process, skip to the next step so you can begin. If you're interested in how I made it, keep reading!
To create the 3D model, I observed a normal transforming picture cube that I owned and boiled it down to 2 things: transforming cubes are made of 8 smaller cubes, and are bonded by 8 hinges. Thus, I would only have to create one cube and one hinge, and then duplicate each 8 times. However, to make a transforming star instead of a transforming cube, the inside of the shape must be different than the cube interior. After doing some research on some 3d printable transforming stars, I found a way to create the hidden star on the inside.
To make each sub cube, which I'm calling a cubie, I used Sketchup. First, I created a 2"x2" square, and extruded it upwards 2" to create a 2"x2"x2" cube. From there, I deleted the three front faces of the cube, exposing the insides. To make the hidden star shape, I drew lines to connect each of the opposite corners (see the pictures above). After that, the cubie itself is done! Too make the bonding strip, I simply drew a 1/2" by 2" rectangle. This is all that's needed for the units. From there, I exported the objects as a .DAE file (Collada file).
However, Pepakura (a mesh unfolding software for paper templates) primarily supports OBJ files, so I needed to convert the .DAE to a .OBJ. To do that, I used Meshlab to convert the file type. All that was needed was to open meshlab, import the dae, and export it as an obj.
The next step is to unfold the mesh in Pepakura. Since I have a mac, I used a VirtualBox Windows 10 virtual machine to run Pepakura (which is only Windows supported). I opened the obj file in Pepakura and hit the unfold button. Pepakura by default attempts the keep the object connected, but since the outside of the cube and the inside of the cube have to be different colors, they must be separated. Thus, I split the square faces from the triangle faces in a way I felt would be easy to assemble and arrange on a template. Once I was happy with the arrangement, I printed the Pepakura as a PDF using CutePDF Writer.
The final step was to make the template and duplicate each unit an appropriate amount of times. Each cubie has one piece for the outside, and 2 for the inside, and 1 bonding strip. Thus, I opened the PDF in Adobe Illustrator and made 16 copies of the inside piece on one page, and 4 duplicates of the outside square faces and bonding strips. I scaled all the parts down a bit to fit all of them on, which is why they don't match the 2 inch dimensions I made them as. After saving the new PDF, I duplicated the last page, creating a total of 8 outer pieces and strips. I added my logo and info, and I was done!
If you are interested in any of the files I mentioned above, I have attached them all below, including the SketchUp, OBJ, DAE, the Pepakura, and of course, the template. The Pepakura file is especially helpful if you are looking to scale the model up or down. You may not be able to open the SketchUp file depending on what version of SketchUp you have, so if you have compatibility issues, simply import the DAE file. You can also use 3dwarehouse.sketchup.com to convert it into whatever version you need.
Now that you know what took to design the geode cube, let's move on to actually making it.