I made this mount for the dial indicator to level the bed of my Prusa Mk2.5. It is designed to work with this indicator:
https://www.amazon.com/gp/product/B07888LX1R/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1
The indicator mounts onto the extruder, takes the place of the part cooler fan and the shroud (it uses the top mount hole of the fan). I added standoffs for the screws so you can use the screws you just removed (the fan screw is longer, so is the standoff). There are two STL files, a single piece, and a three-piece version, The holes in the back are countersunk for the tiny screws that attach the back to the indicator. For that reason, it's much easier to print the back with the wider holes facing up, but then you have to print standoffs separately. If you can manage the overhangs, you can try to print it as one piece.

After the printing, clean the small holes with a thin drill bit (the tiny screws that hold the back are quite delicate, easy to strip the heads, don't use them to clean the holes in the plastic if they don't fit easily.

If you print the 3-piece version, you now have to glue it together. The shorter standoff goes to the long arm, look at the one-piece model for reference, I used basic superglue, there isn't any force on these joints, but you have to align them. Use an M3 screw or the hex wrench to align the holes.

After the back is mounted, take off the fan and the shroud and mount the indicator. Take the measurements above every mounting screw on the heatbed. You can compare the values with the cold bed and the heated one. I found that the values change, but the differences remain almost the same. The highest point will remain unchanged, every other mount will be shimmed up, so compute the differences in height.

Now it's time to print the washers to level the bed. To make it easier to install the washers, I gave them handles: the long one is for the central mount that is hard to reach, the short one is for the corners. You have to change the washers to the correct thickness first, either edit the STL or rescale them in the slicer. Set the layer height so one or more layers add up to the desired thickness (the first layer does not have to be 0.2mm, you can do 0.15mm, so that is about the thinnest you can do). I printed them from PETG. Thin washers may be difficult to remove from the bed without tearing them, so use blue tape, it gives good enough adhesion for one or two layers, and you can peel it off the bed, then roll it from under the washer.

While I expected the process to be iterative, I found that there is no need: after installing all the washers, I got near-perfect leveling, according to the indicator. Remember to rerun Z calibration and reset manual bed level corrections to zero. I could never get the calibration target print right before, the corner squares were off. After leveling, it printed on the first try.

Prusa

i3 MK2S

No

No

0.2mm

20% gyroid