Flying Extruder Suspender

Using a flying extruder like this one can shorten your retracts from 5-7mm down to about 2mm, because it will shorten your Bowden tube's length from ~450mm (for a 750mm tall printer) down to ~150mm. If you have a taller printer, this is an even bigger win.

This can work with a variety of extruders, but I'm using it with Shane's: https://www.thingiverse.com/thing:245677
I've used the Shane's extruder on about 15 printers, and it has been very reliable. I like that it is easy to load, compact and that it doesn't use any unusual parts.
I use the variant which uses an M4 nut to secure the Teflon tubing and a Mk8 drive gear.

To build this, you'll need:
* 2x M3x16 SHCS
* 2x M3 nuts
* 1x M3x10 SHCS
* 4x M3 nylock nut
* 3x 190mm long pieces of 3/8" OD, 1/4" ID rubber tubing. (These three pieces need to be slightly longer than half the length of the horizontal extrusions in a Delta printer.)
* 1x KeyBak (heavy duty): https://www.amazon.com/KEY-BAK-Retractable-Stainless-Polycar