This is a large Sierpinski triangle, designed to be printed in four pieces and glued together.

Instructions

Print one of the Center, and three of the Corners.

The corners and the center have tabs and notches to allow precise alignment, though depending on your printer's tolerances you may need to trim them with a hobby knife to get a good fit.

Glue the corners onto the center.

For more about Sierpinski triangles, see http://en.wikipedia.org/wiki/Sierpinski_triangle