Yup been there, done that. I now use two flat sanded us quarters and VICE GRIPSI actually read about using a garlic press when I was researching using the refractometer and it sounded like a great idea. That being said, I just tried pressing three leaves from the "Vulxed" Dolato. Using three leaves should give a better "average" than using only one.
What I ended up with was minced MMJ leaves and NO juice to test!
I found this style but suspect its just a fancy Garlic Press