Dial gauge indicator holder for manual bed leveling

Designed for Creality Ender 3:
I have a warped bed with a well in the middle. I want to use the magnetic plate but the warped bed gives a headache.

This is a set of accessories for manual bed leveling using a dial indicator.
It can be mounted just with pushing it on the hotend carrier cart plate (from the top).
The measuring tip is appx. 10 mm in -Y direction [0,-10] from the nozzle; still much closer than other methods. Your configuration may vary.

NOTE:
In my configuration the Shaft and Cone (the measuring tip) is located below the printer's heat block. Be careful.

The real photos are showing the first prototype but the second version is very similar. See the models.

How do I use it?
I have the manual_bed_leveling enabled in Marlin. I can launch the procedure of Bed_leveling in printer's menu.
- First, the assembled Holder with gauge is placed on the Hotend cart plate.
- Activate the Corner bed leveling in menu
- Adjust bed height wheels to read all corners at same elevation on the Dial scale
- Activate Bed leveling procedure in menu
- Go through all measuring points and adjust the Z offset on screen by turning the control knob to read the same elevation on the dial (same as corners)
- When finished, Store settings in menu
- At last, the Live-Z method of finetuning the first layer shall be used
- Use the menu option during printing: Tune -> Z-offset (adjust to have perfect first layer)

After this procedure the first layer shall be very homogenous across the warped bed.

Print settings:
Dial holder shall be stiff use several perimeters, layers at 0.2 or 0.24 mm.
The Cone is small, use low speeds and layers around 0.08 mm
The Shaft bottom part shall be stiff, use enough top and bottom layers (4+4)

The Dial Holder is inspired by another gauge holder, I need to find the reference to express my gratitude to the author for inspiring me.