Wagon Wheel Pi Approximation
Let there be 2n+1 spokes of the upper half of a wagon wheel. Divide the semicircle vertically into 2n+1 evenly spaced segments using bars. The intersections of the spokes with the corresponding vertical bars creates truncated spokes where the middle vertical truncated spoke (inferred from the pattern) approaches 2/
Credit
"Wagon Wheel Approximation of Pi" from the Wolfram Demonstrations Project
http://demonstrations.wolfram.com/WagonWheelApproximationOfPi/