Originally Posted by Greg Needel
The easy answer is find someone with a wire edm to make them for you. You can do pressfits with a reamer on a lathe, but the issue with these is that every gear that I found that was off the shelf 11tooth already had a bore which was over the pressfit size. So you would need to find a source for some gear stock (if you find it let me know I couldn't find any. )
You can get 12T 20DP gearstock. Obviously not quite what you have, but if a team were to be satisfied with a 12T already and just wanted to press it on, that would be a solution.