I got tired of guessing how much filament was remaining on the spool, would I have enough to finish the project? Using an arduino uno r3, and a load cell, I set out to solve my problem. I used the arduino tutorial from random nerd tutorials ( Arduino with Load Cell and HX711 Amplifier (Digital Scale) | Random Nerd Tutorials ) to program the arduino, and modified the large spool holder from ratrig ( Official Modifications - Rat Rig Lab ) I used a breadboard to wire up the arduino, scale, hx711, and button, then laid it all out and soldered it to a prototype shield for the arduino. I used jst connectors for all the connections, and then made a wire harness to connect the .96 oled display and tare button. Overall it was a fun project, I've never used arduino before so that was a learning experience. I would say one of the drawbacks is that you still have to estimate the weight of the spool itself. but for 1kg spool I estimate 250g for a plastic spool holder. But you get a much better idea of how much filament is left. I'm adding the step files, feel free to remix and make it better or make it suit your needs. I'm using this on a ratrig v-core 3.1