4L puzzle

4L is a packing puzzle designed by Yasuhiro Hashimoto, crafted by Mine and awarded by an honorable mention at IPP 2015.

The puzzle is composed of some plexi, a wooden cage and 4L shapes pieces to pack inside the box. To be more precise you have 2 pairs of L: one kind of L piece is a bit thiner.

The goal is easy and the puzzle looks so easy....Well how can a puzzle be hard with only 4 pieces you can wonder. Well, wonder more! :-)  This is a difficult puzzle and it has given a lot of pain to the puzzle collectors who have this (nice) puzzle.

Indeed you have many ways to pack the pieces and you have also rotations. Some rotations are (or seem?) impossible, other are not that difficult, but in any case you need precision. 
I worked on this puzzle for long time and at some point I thought it was impossible and that there was a fit issue with my puzzle...sign of despair maybe...I could not really find other collectors who played with it (or solved it), so not easy to get some hints.

I worked again a bit later on the puzzle and tried to focus myself of the shape of the plexi and how I could use the space between the plexi and the pieces, trying to see which piece can go between this space and in which positions. No success but I tried.

After I came back to my first ideas of how to pack 2 pieces and then how the 3rd one could be put inside. At the beginning I tried to pack the pieces outside of the box with the constraint of the 4th piece but I could not really make progress. So well, I came back putting pieces inside the box, that's the goal, right :)
After a sequence of moves I managed to put the 3rd piece and after some sequence of moves the 4th piece was packed! A very satisfaying puzzle and it's worth the money!! And the solution is easy to repeat. I fear burrtool won't help you because of the rotations...But your brain is more powerful, isn't it?

I always have the feeling that packing puzzles are too frustrating because of all the possibilities to pack the pieces and solving a puzzle should not involve frustration but satisfaction! So when I buy packing puzzles, I try to choose the ones that have a little something different regarding the solution or the design. I was right to buy this packing puzzle because of the "ah-ha" moment with the 3rd piece packed and because you realize that a puzzle can also be difficult with few pieces!

All pieces packed, but this is the only orientation where it does not spoil too much