Summary

Floating Extruder (for lack of a better name.... Bob up and down extruder)

Used with a Delta printer. I use it on my Mini Kossel Printer.
Designed to use a Wade Extruder.

Allows the use of a bowden extruder setup without needing to have bends in the bowden tubing. Allows for shortest possible length feeding tube. Because the tubing stays straight, there is a reduced force needed to push plastic through the bowden tube and needs less retraction. Also the bend in the bowden tube doesn't put lateral forces on the end effector. I got annoyed when my printer needed to retracted repeatedly and kept tearing up the filament resulting in failed prints. Now I can print really fast and with great results.

Cons: Makes the printer really tall (basically doubles height)

The extruder moves up and down with the end effector which puts less forces on the end effector when printing. The elastic band adds a counter lifting force so there is very little force needed to move the extruder up and down.

Parts:
2 - lm8uu bearings
2 - 8mm rods (length determined by print height)
1 - elastic banding
1 - Wade Extruder with bowden

Printed parts:
1 - Riser
1 - Top_Riser
1 - Riser Bungee Clip 1 & 2
1 - Roller
2 - Riser Mounts