Model originally uploaded to Thingiverse at https://www.thingiverse.com/thing:4088469.
This is a remix of my other flying extruder. If you're using the stock extruder motor, you want that one instead. This one was specifically designed for 23mm NEMA17 pancake motors, like the ones from Zyltech.
I'm using a gear-reduced dual-drive (Bondtech BMG clone) extruder, so the stock motor is serious overkill, this one works great.
I designed this so a simple 3mm cap-screw could be used in each of the holes to attach surgical tubing (with a zip tie) going to the carriages. Then I found these mini-bungie cords at Home Depot, so I made the bungie-loop to mount them. They turned out to be the perfect length. The position of the holes for the bungies (whatever type you end up using) was as close as I could get to evenly distributing the mass among the 3 carriages. This does make the rear bungie a bit loose (if you use the ones mentioned above), so I simply tied a knot in the cord behind the metal hook to shorten it up (if you see the design of those bungies, this will become obvious). Because of how lightweight this motor is, I may just remove the knot and shorten up the remaining bowden tube even more. This lightweight assembly doesn't seem to need any counterweight at all, so I've removed the bridge and top attachment points.
After installing this, I dropped my retractions all the way to 2mm. After switching the bowden tube to a 1.9mm ID one, I was able to drop my retractions to 0.4mm! The cube in the pictures was printed in 3D Solutech See Through Blue PETG. The two things that helped the most were this flying extruder setup and my corner reinforcements.