A lot of free time, and to be honest, it’s been many years since I created these sprites. I’d need some inspiration to go back to this style and create more sprites at this point.
I cannot help you with the free time. However, would it be an inspiration to get a free game that uses these sprites? Actually at this point I would be very happy just to have a little bird in this style. If you need financial inspiration I can help also. :-P