The outside part with the fan attachements, LED ring & magnetic stud ball attachements are sourced (with a few modifications ) from Haydn Huntleys "Magnetic Effector with 3 Fans and LED Light Ring for Kossel Plus" found here: https://www.youmagine.com/designs/magnetic-effector-with-3-fans-and-led-light-ring-for-kossel-plusI use the same magnetic ball studs that Haydn sells for a reasonable price, 12 are needed for a complete printer.The ball studs are exactly 39.7 mm apart, to match the distance between the outer holes in OpenBuilds 20mm V-Slot™ Gantry Plate that I'm using as Delta carriage on my verticals.Update 2016-02-22: Moved fan lugs by 60 degrees for better aim at the tip of each hotend. Also, this frees up some space between the effector and the idler belts.
Technical
* six magnetic ball studs from Haydn Huntley:
http://www.kosselplus.com/
*6 M3 Nyloc nuts for the ball studs.
* PolyStroooder Tri Hotend:
http://polystroooder.com/
* LED ring with outer diameter 60mm and inner diameter of 50mm, can be found cheap on eBay or AliExpress amongst other.
* Up to three 5015 centrifugal fans similar to these: http://www.ebay.com/itm/6-pcs-Brushless-DC-Cooling-Blower-Fan-5015B-12V-50x50x15mm-2-Wires/141324730524
* an M3x25 socket head cap screw and M3 nut for each fan.
* some M3x10mm socket head cap screws and M3 nuts, if you use the groove mount. (I used M3x8mm, because that's what I had at hand. It works too with a bit of ingenuity)