Each dovetail has different mechanism: the first is easy and you should not have any difficulty with it, the other 2 have some tricky mechanism that will challenge you a bit more.
Each dovetail has 2 wooden parts and the devetail joints have a strange shape, well that not the usual shape for these kind of puzzles. And the trick is also, when you have unlocked the mechanism, to slide the 2 parts in the correct way, which needs a bit of practise. No force required!
The craftmanship is very good and very precise. Well, precision is the key for dovetails.
After some time and pain in he hands I managed to open all the dovetails. I liked all of them and there is a real progression from one to the other puzzle. I think this is nice to have made a series of 3 puzzles and not just one puzzle: more puzzling fun! I also like that Eric does not produce a lot of dovetails so, it changes a bit and this is very appreciated.
I won't comment on the precise mechanism, I will just tell you that it's not super complex inside, but well implemented and very efficient.