UPDATE: There are 2 versions of this design
This is a remix of the thing: http://www.thingiverse.com/thing:1746358
I've also remixed a design of mine (http://www.thingiverse.com/thing:2090644) to make the final design.
Since I use a induction sensor to the left of my printer's extruder, it wasn't possible to place the induction sensor to the left of the extruder. The orginal design has the extruder fan facing to the left of the extruder, so I decided to remix it with the fan facing to the right side.
Made by reverse engineering a printed version of http://www.thingiverse.com/thing:1746358 using a caliper.
I made this remix because I liked the original design, but it was extremely difficult to remix it using the *.step file provided for download. Hope that this remix makes things easier for editiing the design. That's why I've included the original FreeCAD file, used to design the parts of this THING.
02/10/2017: There are 2 versions of this file uploaded. Version 1 has a 22mm internal diameter and version 2 has a 23mm internal diameter. The 2 versions were made due to possible issues with material retraction after printing.