It's been a long time since I've tried any mechanical puzzles. I bought these almost a year ago, and only now have gotten around to them. The first one is the Transparent Lock by Gary Foshee. The object is just to remove the clasp. Not very hard, but extremely well made.
The second puzzle is called Larva and the object is to slide the metal pieces around so that the coin can drop off. Robrecht Louage. Not too hard, but there's a nice surprise.
MoYu is a twisty puzzle that's actually 2 puzzles in one. The circles - I first saw that feature in Smart Alex from 25 years ago. Otherwise, it's not that hard.
Cast Keyhole - Hanayama Metal Puzzle comes from Vesa Timonen. I've taken them apart but haven't restored it yet. Vesa has produced some very cool mechanical puzzles in the past.