# Magnetic 3D Puzzle

##### November 1, 2016

## Idea

A dodecahedron is a 3D shape with 12 flat faces. This shape can be decomposed into identical triangular sections, which can then be assembled together to form the dodecahedron, in this case each triangular section has a raised point forming a stellated dodecahedron. This project is a 3D puzzle, where each triangular section contains magnets that attach to the nearby sections, and the goal of the puzzle is to match all the magnetic poles in assembling the completed shape. With two opposing magnetic poles, and three sides on each puzzle piece, there are 4 unique pieces (the triangle rotational symmetry removes 4). Additionally there are symmetries on the dodecahedron shape itself, which limit the unique solutions to the puzzle.

## Supplies

- 3D printed triangular pieces
- Neodymium magnets

## Construction

Geometric formulas are used to establish the desired vertices of a triangular section, then a 3D sketch is made in CAD, and a hollow shape generated for the 3D printer. Then all the sections are printed.

*3D printed sections.*

Next magnets are attached inside the sections using hot glue. A few sections are configured with random magnetic poles, then subsequent ones are matched to make a complete dodecahedron.

*Left, 5 sections joined together. Right, putting in the final sections to close the 3D shape, with matching magnetic poles.*

## Results

*Completed puzzle.*

The puzzle fits together successfully, and upon taking apart the pieces and scrambling them, is easy to put back together, requiring a bit of trial and error but doable within 1 minute. Its 3D appearance makes for an interesting decorative item or conversation piece. The magnetic connections are just strong enough to hold the shape against light pressure, but it has to be handled gently and is not really transportable in the completed state.