This is a toolpost dial indicator holder for the metal lathe. It fits AXA quick change tool posts, and is sized for standard Mitutoyo dial indicators (or similar). It's a really quick way to throw an indicator on your QCTP to dial in the 4-jaw chuck or measure run-out in a part.
This was deeply inspired by this project from mrpete222 (your YouTube shop teacher!):
I remodeled it in Fusion360 and tweaked the dimensions for full-size dial indicators, rather than the small Shars ones. The mounting hole is chamfered for a 45° allen head machine screw, like you'd find in Ikea furniture (which is exactly what I used). This keeps the hardware flush with the holder and clear of the tool post.
The Fusion360 file is included, so you can easily tweak it for your indicator or your desired mounting hardware.
Prints great in the upright orientation. No rafts or anything needed- this is a very easy print. 20% infill is fine, because this part doesn't need to be enormously strong for what it is doing. Dimensions assume PLA (other materials make shrink or distort such that the dovetail may not fit properly).
The STL file has this laying on its side, because that's how Fusion insisted on exporting it. Print it with the dovetail running vertically for a good precision fit on your tool post.
I printed this on a Printrbot Metal Plus, but Thingverse doesn't have that in their settings, so I specified Simple Metal.