Balloon Fractal: Sierpinski's Tetrahedron

Sierpinski's Tetrahedron is an awesome fractal to make out of any material, including balloons. First you'll need to know how to make a tetrahedron. Then, you'll need a lot of friends, or patience! Make as many tetrahedra as you like, as long as it's a power of four, and then put them together in the following iterative way.