I've always been a fan of salted eggs even though they're unhealthy XD
With my bad experience with salted eggs recently (I had black salted eggs on 2 occasions!), I really wanted to make some. As duck eggs aren't sold in Singapore, I resorted to using chicken eggs.
Taking reference from Christine's Recipe, I purchased a huge glass jar having spotted it being on sale at Crate and Barrel 2 months back. The jar I had was HUGE. I had about 28 eggs in it! Of course, scale down the recipe to suit you. I reckoned that since I was gonna make some and that they take 30 days or so to be ready, I might as well make a huge batch of it.
I'd rate it a difficulty level 2 out of 5.