Inspired from http://www.thingiverse.com/thing:145946, but it's only inspiration :) I've modified the thing a lot. It has a more aerodynamic structure to cool down every part of the ramps. One side is closed, because the air coming from the fan cools down the heatbed a bit. It's made for 40mm fan, but you can customize everything, even fan position, by playing the scad file. It prints nice without a support. The legs are a bit fragile, so be careful.