This thing was made with Tinkercad. Edit it online https://www.tinkercad.com/things/dVZJpZ6zQLA

Deltaprintr

Deltaprintr Kit

No

No

100%

Black PolyMax at 185 degrees, 60mm/sec.

This is a mod of the original...
http://www.thingiverse.com/thing:1195771
by Dpbailey to include holes and a center sleeve so the 2 fans can cool the hot end too.
I don't know if it is a good idea yet but hope to have a try later.

I have reduced the height of the cylinder that I originally added by 2mm as it hit the hot end plate.

The unit is running well on my Deltaprintr.

The heater is wrapped with PTFE pipe jointing tape to help insulate it from the cooling air of the fans, and that also holds the thermistor in well. Also, the thermistor has thermal heat sink compound around it in the heater block hole to help temperature accuracy.

There is a second duct that has recessed spaces for the heads of the arm mount screws but I have not printed that one or really checked the recess positions.

The fans I used are from Jaycar...
http://www.jaycar.com.au/Electromechanical-Components/Fans-%26-Accessories/Axial-AC-DC/40mm-12V-DC-Fan/p/YX2502
They have thinner fans too and using them would be ok to save mass at the loss of some air flow. Also a pair of fans from Ebay would save lots of $$$.

So far I'm very happy with the results. Thank you Dpbailey :)

May 2017 EDIT:
I've added version 4. It has a cut out top so it can fit higher up allowing a LED ring to be placed under the fan assembly. The LEDs just run off the fan supply so they flicker a bit and I can't be bothered fixing that.
All held together with hot melt glue!
This mod came about as there was a failure with my Deltaprintr that caused it to stop moving and just keep in extruding. This filled the fan duct up with plastic. Fortunately, after heating it all up again for a while I managed to get it to come off. So I took the opportunity to mod it again.