You could use a foam brush and Revell model toy color in matte black
https://www.amazon.com/Swab-its-Hobby-Tips-Durable-Reusable-Applicators/dp/B0921BKJ8J/ref=sr_1_12?crid=1QE6PT144NW7E&keywords=foam+paint+brush&qid=1687594714&sprefix=foam+paint+brush%2Caps%2C254&sr=8-12