This is a holder for the NeoTeck Digital Indicator to mount on the extruder of an Ender 3. The indicator was the cheapest one on amazon. The holder should work with an digital or dial indicator with an 8mm shaft. The triangular hole is to accommodate screw that holds the top of the fan housing to the extruder mount. The holder hooks on the top x axis carriage and the bottom the the fan housing. The dove tail joint is so the part can be printed with no supports.

This was designed in TinkerCad. The dovetail will most likely require some sanding to fit. It needs to be tight, but not so tight as to crack anything.