This may look like a simple 2x2x2 cube, but I assure you it's not. This is my build of the Nightmare Cube made from design by Adam G. Cowan. It's a bandaged 3x3x3 inside, and a 2x2x2 outside. Initially the puzzle turns freely on all three planes, but after just one move that isn't the case.
I've made several attempts to build this cube. It turned out to be not that straigtforward as it might seem. You have to be extremely precize in making certain parts or the 3x3x3 inside will not quite align, and it's very noticeable even if that's only 0.1mm or 0.2mm. All attempts yielded workable puzzles after I removed the plastic that stuck out becase of alignment imperfections. Unfortunately I am a perfectionist, and I was not satisfied with the quality, or simply the fact that it can be made better.
This is my latest attempt and I can say now that it yielded a perfect puzzle that I completely satisfied with. Everything is aligned perfectly inside, and as a result the puzzle turns beautifully easy.
I guess, that's about it.

I'd like to sell this puzzle, and therefore would be interested in hearing offers if there is interest. To answer possible questions, Adam has given me his permission to do so.
Video of the Nightmare Cube.