I know I said no more posts about children toys, but this one was a really good find. If you work with 3D entities drawing in paper will get you only so far. At some point you really need to look around, hold it in your hand.
Last time it was a voxel playset. This one is a "simplex" playset:
A simplex is the the minimum geometric unit you can have. In 2D they are triangles, in 3D tetrahedrons and in 4D, well, you do not really want to go there.
They matter because when you are looking for a solution to a problem, it is often best to target the simplest element possible. If your solution is based on them, it is likely to be the simplest solution as well.
It is no coincidence we use triangles extensively for rendering. In 3D simplexes are equally useful. For instance, Perlin rewrote his famous noise function to work over simplexes instead of cubes. It resulted in a faster, better looking noise, which Perlin aptly named -you have guessed- "Simplex Noise". At this point in time, there is no reason why someone would use Perlin noise when Simplex noise is available. We also have Marching Tetrahedrons, which improves over Marching Cubes.
In my case I was looking at them because of their role in interpolations. Trilinear interpolation is often done in a cube. If you do it over simplexes you can shave off a few multiplications. When this is in a hot area of your code simplexes can make a difference. And above all you also have an excuse to play with these cool toys. Did I mention they are magnetic?