Print with a 0.4mm nozzle max. Adaptive layer height down to 0.1mm because there's fine detail. 

Print both parts with the flat face down and use a brim. No support should be necessary. 
Print them one at a time for the best result to reduce stringing. You will need to deburr/chamfer the bottom edge with a sharp knife or sandpaper just to ensure a proper fit and removal of the brim. 

Holds a BIC Round Stic. I prefer to fill mine with the larger 1.2mm ballpoint for extra-smooth performance. 

The included cover photo shows versions modified with a name and a clip. The models provided here are just the plane pen with no modifications.