When doing a google search using the terms "custom drum sticks" I'm getting a huge amount of matches.
This forum - as most if not all forums - has a secret weapon called search function, too.
So what I did was... using the search function and searching for "custom drum sticks". As expected, a good number of matches. Check them out - many/most of them might be irrelevant for your need but browse thorough some of those threads and you should find some custom drum stick manufacturers that people are happy with.