For my one foray into ML, in 2020, I also built my own labeling system. It was stupidly simple; IIRC, it was a Jupyter Notebook that presented you with text to label, and you’d do so by hitting 1-5, which were mapped to sentiments / emotions. If you got bored, or just wanted to see how it performed with X% training, you could save progress and quit. It worked well enough, and I think I labeled a couple of thousand entries using it.