The original meter can be found here:
I made this one for my Anycubic 4Max, for more information check the original link above.
UPDATE: I had to update the design, the O-Ring was making the wheel less travel, the updated version is up as v2, more details about new O-Ring is in the original file description.
Since it is hard to put anything on 4Max I made this one fit between the filament tube coupler and the filament sensor. I think it will work with the OEM spool holder, but I am not sure.
You need 2x 30mm M4 screws, the filament sensor can be mounted with the original M4 screw.