I had been looking a tiny little bit into the Greek course some months ago, then dropped it again for the time being. I still feel a need to familiarise with the Greek letters, so I thought about ways to play with them.
I would have liked some flashcards that would only have a picture and audio and make you type the word, but I didn't succeed creating such thing on Quizlet.
Instead, I created a very simple crossword puzzle with some of the first few words taught on Duolingo.
It may be suitable for printing and handwriting the letters, but as I wanted to save paper, I used an image editing software to enter the letters.
Maybe someone who is also working through the very first lessons happens to like it.
Intermediate: 
Lower intermediate: 
Beginner: 
Absolute beginner: 
A1