The main difference between this and a common scale is that this device has the possibility to add multiple profiles to store different Tare values so that way we can measure only the weight of the remaining filament excluding the weight of the empty spool, because each brand of filaments has a different weight and material for the spool itself.

Features:

It can measure weights from 10g to 9999g.

There are 3 buttons (LEFT, ENTER, RIGHT) that can be used for scrolling through different profiles and navigate through the menu system.

You can add, edit and delete profiles using the menu system. It can store up to 20 profiles, with their own name and Tare value. Maximum 21 characters for the name of each profile.

You can do a full calibration for the load cell using the menu system, so there's no need to edit the sketch in any way.

Configurable deadzone with real-time reading on the display. The deadzone helps ignoring the fluctuations of the constant pulling/pushing of the filament in the 3D printer so we show the most realistic estimate of the actual weight left in the spool.

All the settings are stored in the EEPROM so it's going to remember all the settings after powering the device off.

There is an option in the menu to FACTORY RESET arduino for clearing the EEPROM (user data).

Auto-center the tittle text in the main/normal screen ignoring spaces to the right.

When adding a new profile, it's going to save the new profile after the current profile so the order can be arranged in a predictable way. To make this work it required a lot of effort so even though you might take this for granted, it's not a trivial feature.

When powering ON, changing profiles or returning from the menu, it shows the weight starting at the lower edge of the deadzone so the device is ready to measure the decrease of weight of the filament immediately.

No timeout for being on the menu. Yes, that's right, this is a feature. Why? I hate timeouts that will exit the menu if no operation is done after a few seconds, but I think that is a bad design that causes stress and frustration because you feel like you need to rush things with the threat of having to start all over from the beginning. You are not going to find anything like that in here.