This is my view on a delta end effector and matching carriages. I use them on a Kossel XL with 245mm diameter build area. They are designed to be used with Haydn's Carbon Fiber Arms and E3D v6. Arm spacing is 60mm to improve stability. Design goal was to raise the hot end mount higher in order to maximize the build volume.

There's a place for two 30mm axial fans on the effector for part cooling. Cooling shrouds are included, but they are untested, most likely less than ideal design and may be too high (reaching below nozzle tip plane). However, the cooling shrouds are not an absolute must IMO, print them and test them if you like.

You need two pieces of the E3D v6 mounts, might be good to use something more heat resistant than PLA for those e.g. ABS or PET-G, other parts should be ok in PLA. The standard 30mm E3D v6 cooler shroud with 30mm fan can be used if leaving out the two lower fan screws or slightly modify the effector to make all four screws fit.

The carriages have 20x20mm mount hole pitch for M3 bolts, compatible with e.g. MGN12 linear guide rail sleds. The carriages have no belt tension adjustment as I use separate adjusters.

Please note that most of the parts need to be rotated before slicing to appropriate printing orientation.

Edit 2018-09-27: Added '180_fanduct.stl', a directed fan shroud. It's a bit tricky to print, but I've been using this shroud for some time and seems to work ok.

Edit 2018-11-01: Replaced both the previous part cooler fan ducts with a new design Fanduct.stl. Two needed for dual part cooling fans.

Edit 2019-10-13: Added a new lighter version with a wire loom guide and new carriages with integrated belt tensioners. Included a fan duct extension for compatibility with E3D volcano nozzles and heat blocks.