Auto Filament level indicator

This is Auto Filament level indicator that use a plastic spring to indicate amount of left filament.Set minimum layer time to close to 10s while printing front leverBoth front and back lever have to be glued in place as shown in 3rd pictureBoth lever must be perfectly aligned/parallel to each otherthen device can be mounted on spool with tissue tape or double sided tapeNOTE :- This model is based on Numakers spool dimensions there could be minor inaccuracy in measurement for other brands