This design is retired and replaced by this one that uses 2 blower fans and has LED lights in the base.
Based off a number of other similar designs, this fan setup uses 1 x 40mm x 10mm axial fan for the hot end cooling. On the sides are two standard 4020S blower fans.
The print, with the two fans weighs 78g.
I tried to keep the whole design as small as possible so the head can reach the outside of the print bed without the fans hitting anything.
Update: Feb 6, 2017 - If your effector doesn't use Traxxas joints but uses the larger bearing ends, use the fan STL labeled "Extra Clearance". It drops the fans low enough under the effector to clear the large bearings, but maintains the original height of the design.
Update: May 14, 2017 - Uploaded an adjustable vent version for those that want to direct the airflow. The STL files have the "ADJ" in them. I am using it on an E3D V5 but I don't think it enough to accommodate an E3D V6.
While the fans can be connected to a RAMPs board for control, I prefer manual control so I connect them to a simple PWM control found just about anywhere on the net. The majority of the time when cooling is needed on a print, I have the PWM control pot set about 60%, when doing single wall vase mode, 80% or more if printing something like a rocket nose.
The fans are mounted in such a way that the Traxxas rod ends will not touch the fans. The effector mount will also clear the fans.
The Kossel/Delta I am using this on has an effector plate with 40mm spacing mounts so it's not going to fit on a Mini Kossel. The hot end I am using is an E3D-V5 and the nozzle extends 6mm below.
M3 screws are used to attach the fans ( 3 per blower fan, 4 for the axial head cooling fan).
For the adjustable vent version, be warned the vents are a SNUG fit! I print the vents with 50% infill, slow (30mm/s) and 0.2 layer height. The hole in the fan housing is 10mm and the vents are 10mm in diameter. If you want some wiggle room, scale the vent pieces ever so slightly. I prefer them tight so they don't ever move once adjusted.
Note also that the fan setup will only work with Traxxas rod ends.