This adapter allows to attach a indicator dial to the print head of Bambu Lab Printers (P1P, P1S, X1, X1C)  to measure bed flatness.
I am using a STEINLE 3105 (EAN 4251285620469) to do the actual measurements.

If the adapter does not fit in easily do not force it, do some light post processing and try again.

The adaoter attaches to the hotend mount with the orginal screws.
Install the adapter to the tool head without the dial, otherwise you wont be able to tighten the screws of the printhead.

Then attach the dial to the adapter and tighten clamp by screwing in a M3 skrew from left sight as seen on the picture.

The adapter attached to the hotend mount. Here is the link to the Bambu Lab Wiki on how to remove the hotend:

Replacing the complete hotend assembly / Nozzle Replacement Guide | Bambu Lab Wiki

Here is the link to the video how to use it to measure print bed flatness:

Bambu Lab X1C/P1S/P1P Bed Flatness Measuring - YouTube

Her is the link to the onshape document with the raw CAD:
https://cad.onshape.com/documents/728090a3ece9140b58c556ae/w/434a9762db11f9e184157593/e/3f580b98fe888e73e68fbb12