Grooved Three Piece Burr

I love 3 piece burr puzzles. This one shows that old ideas can be a good way to have new ideas. Not too hard, but confusing enough.

I love puzzles that have a small number of identical simple pieces that come together in interesting complex ways, and this is a great example of one. It looks like the pieces should go together in a straightforward way. But that annoying pin keeps me from sliding that piece where I need it. And that other piece won't give me room to put another of the pieces in because its pin is in a slot and won't go far enough. Even when you figure out how you think they fit together it's not clear how you'd get them there. While not excessively hard for a seasoned puzzler, even so it's definitely a non-trivial solve, requiring a little bit of aha to get the interesting move sequence to solve the puzzle. And the biggest compliment: even after I solved it I kept playing with it - the movements and the solution are just so fun.