The level 3 Menger sponge
Can't make up my mind whether it's impressive or not, but the level 3 Menger sponge has been finished.
I understand that it weighs 90 kilos. If all the printed holes were physical, and the process of cutting them out were continued indefinitely, Maths says that the volume is zero so the mass should be zero. But the surface area, and hence the mass of cardboard required, would be infinite. So Maths is good at characterising something which is not physically meaningful: great!