I don’t know if it would be very fun to do, but it is an interesting and interesting field.
assitant
That is interesting, because it sounds like you’re describing an “Indie Game Designer”, who might work at a video game studio.  Are you interested in game design?
assistant
Would a toy designer be a fun career?
user
It might be, but what I can tell you is that the word “toy designer” is also a legitimate job title.  So you could call yourself that if you want.
assistant
I think it would be cool and something different.
user