A while back, I saw this comment:
At first it seemed silly to me, but at least a few people wanted them, so after much delay I went ahead and got them produced. After all, 3blue1brown is otherwise a very non-physical thing: The content centers on math, the visuals are all computer-generated, and it's all distributed over the internet. So I like the idea of there being at least some tangible residue of what I do out there in the world.
While designing them and getting the first batch ordered, I started to get more excited than I expected. Maybe that excitement was driven by ego; who doesn't like to see something they've created come to life? But I think it was also something more than that, I started to get why people might want them.
Contrary to popular perception, math is filled with character. Numbers often seem to have personality, different fields are characterized as much by their style as by their content, and mathematicians themselves are often more enthusiastic about the beauty of their subject than artists. On the channel, the pi creature has come to be a symbol of this unappreciated emotive quality in math, and the plushie pi is your chance to hold a physical reminder of this fact.
You can follow this little guy on instagram if you'd like.
Or you can purchase your own.
There are also a few shirts and posters, if that's more your speed. Also, if you're into nerding out with physical manifestations of math-related things, you should definitely check out Maths Gear. I have no association there, it's run by some other Math YouTubers, but they have all sorts of whimsical trinkets and puzzles that I think you'd like.