What about something easier? Instead of a puffer, just take a big bin of the same part and loop it through the hopper for a few hours. Presto, as much accurately-labeled training data as you want (though limited to a single part at a time).
If I had big bins of sorted parts I wouldn't need the machine ;)
This is an approach that will work for parts that are so common that even after a few runs you have lots of them but the 'long tail' of lego parts is the vast majority of parts and they are quite rare.
