Update
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I updated the gallery pictures to show the new print of this -- the original effector body was an older verison which was slightly thinner. Also please note the probe tower was accidentally printed in reverse due to incorrect wiring but I think it should be possible to deploy the probe automatically if it's printed right (I will validate that soon). If someone finds otherwise I can look into changing the positions of the various mounting holes to make it work better. Please post any feedback in the comments!
Features
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This thing is a basic dual extruder effector for Mini Kossel. It was derived from the Kossel source SCAD with modifications to accommodate 2 hot ends. The modifications are the following:

• Thicker effector for added strength

• Wider center circle diameter to accommodate 2 hot ends side by side (all important Delta measurements remain the same so the same carriages can be used)

• More mounting holes to make up for those obstructed by the new hot end positions

• New fan bracket / groove mount designed for 30mm fan, which attempts to minimize air blown directly on the heater blocks

• New probe tower with reduced footprint to work with new mounting holes

• Optional M5 thread OR non-threaded holes for NPT 1/8" / M10 push fit adapters (I use NPT pipe tap which is cheap and easy to find in USA)

• Optional cone supports to prevent warping of critical cone overhangs

I have been printing with various prototypes of this on my machine for a few weeks now. I think the design is at least stable enough now to be considered "work in progress"

Due to high temperatures I would recommend printing in HIPS, ABS or some other similarly temperature-resistant material. I have found excellent results printing with HIPS perimeters (4-5 layers @ 0.35mm nozzle) and PLA infill (0.5mm nozzle, 25% honeycomb). The PLA infill helps enhance platform adhesion and seems to greatly reduce warping / shrinkage compared to solid HIPS.
All mounting hardware should be the same as the standard Kossel -- that is M3 for everything except the push fit which can use the original M5 OR use a larger non-threaded hole for other types of push fit connectors. I have added nut traps on the fan bracket to ease assembly.
If you are curious about my hot end configuration, I am using MakerGear-style groove mount hot ends from RP1 Labs. These ends normally don't have great heat dissipation but I found some 8MM laser diode heatsinks on ebay which I cut into smaller pieces with a band saw and press fit with a bench vise. I have also tested this effector with standard J-Head hot ends and the result is identical. I use the RP1 ends because they have interchangeable nozzles and heater barrels so I can switch filament sizes easily.