Made this 13T RC Car Pulley as a temporary fix while I waited for aluminum ones, it worked fine for a just as long as the original plastic ones.
(In my photo the green one is printed and the black is stock)
Its basically a replica of the stock plastic pulley from my Sakura D3 CS drift car - but should work for any 1:10 RC situation, has a whole for a pin to the shaft.
Edit: I made 12, 14 & 15 teeth pulleys and also added my c4d file, you can edit the # in the rectangle array to add teeth. sorry, im not cad guy :\