Kevin Sadler wrote about it:
“I have reviewed many Minima puzzles over the last few years. The original idea by Frederic Boucher was to fit various pieces into a 2x2x3 space through a limited opening and requiring various rotational moves which are facilitated by odd holes in the sides of the box. The series has been continued by him and also taken up by many of the best puzzle designers in the world – I have lots of them and love the variety of challenges. I now have several versions of the Minima 13 and reviewed it in June 2025 having taken 4 years to solve it. When I finally managed to review it last year, I said that this 13th challenge in the Minima series was the utter pinnacle of the series – it is quite literally the very best of them all. It takes the original premise to pack the pieces inside and adds extra stuff:

1. It is trivial to place all the pieces in the box without rotations but this is clearly not the solution because…
2. There is a single coloured voxel which must

The goal of the puzzle is to remove the four pieces and repack them, this time with the different colored voxel completely hidden inside the box.