Hi Manuel,
You did see a pot of red legos. My mother has huge bins of legos from when my brothers and I were little and hasn't found anyone to give them to that she knows will use them, so I've taken some of them and made pots. The plants really love it, and you can 'customize' the size of the pot for the plant and change it as the plant grows. The roots don't really stick to lego plastic that well, so it's easy to scooch them off when needed.
It's also kinda fun!
Stacy