Output shaft of the servo will align with hole in brick. There are two couplers to connect servo with LEGO rod. I recommend using the one with additional locking screw, otherwise you may need to tweak the size of the press fit one to firmly connect to the servo shaft. I think it's best to print it with PLA. Supports are not required. Good adhesion to the build plate is needed. Remember that you can always add some glue, but this is last resort.
The author marked this model as their own original creation.