Saw this tweet from Holly Krieger this morning:
and, oh bother, the embedded tweet isn’t coming through. Here it is:
I thought it would be fun to talk about some sort of similar shape and stumbled on this neat design by eduardoviruena on Thingiverse:
eduardoviruena’s “Sierpinski cubes” on Thingiverse
I sent the print to the printer as I was running out the door. Unfortunately in my haste I made the print much smaller than I intended. Oh well . . . we still got to have a fun conversation.
Here’s what he had to say about the eduardoviruena’s “Sierpinski cubes” – I was really interested in his description of how to make this shape:
Because the print was so small I wanted to see if he had any other thoughts when he saw a larger version on the screen:
I’m really excited to do more 3d printing projects like this one – hopefully giving kids shapes like this to play with will help them see a fun and exciting side of math 🙂
Mike's Math Page 
mmmh… it was a long time ago. It was part of my “recursive polyhedra” (or, as a good friend of mine called them: fractalhedra”.
The Sierpinski cube of order 1 is just a cube.
The Sierpinski cube of order n+1 is a big cube and three Sierpinski cubes of order n, one on the top of the cube, another to the right and the last one to the left…
I think that there is a description of the Sierpinki cube in my site
http://michelle.esfm.ipn.mx
it is still working!
Go to the link
http://michelle.esfm.ipn.mx/~mrspock/3DLS/sierpcube3/sierpcube3.txt
Copy the description and paste at the dialog box at:
http://michelle.esfm.ipn.mx/~mrspock/3DLS/
Change the line saying: “rules 3” by “rules 5” or whatever the order of the cube you want to produce.
Press the buttom “send” and you’ll get a “VRML” file that you can change to STL with the open source program: meshlab