As a crew gift on Doctor Who and Sherlock, I’ve given specially designed swag/merch.
For DW S08 I gave a t-shirt and below is the baseball cap for S09. The shirt was designed by the infamous John Smith of WhoLock fame: https://www.youtube.com/watch?v=q3bGYljQ5Uw. The Gallifreyan snapback by the wonderful Sophie.
It was harder on Sherlock because most ideas are spoilers, so I had to have permission to use keywords that were producer-approved. The amazing sculpture-designer, Sarah Peters, http://www.sarahpeterssculpture.com/ was tasked with this challenge: she embraced it and came up with this beautiful design with just “Bloodhound” and “Shark”.
This is the shirt I wore on our White House tour.