An impossible Penrose triangle, created using 3D printing.
I have created multiple variants of this illusion. This is a compact version with cubes. The cubes are as large as in the normal cubed model, but the shape is more compact.
As you may have guessed, given that it is available for sale, it's not really impossible. It only appears that way when viewed from a particular angle.
The shape is an interesting one, curvy and distorted, yet it can easily stand upright so you can showcase this intriguing illusion.