I love Rubik's cubes; I'm a very avid speedcuber. Of course, I've written code to simulate a turning cube. I once modified it to create an infinite grid of reflections; the image can be found <a href="http://archive.garron.us/img/rubiks_mirror.png">here</a>.
So, I decided to try to fit an entire cube into 256 bytes, and after a while, I decided to try to follow that image as closely as possible. For minimalism, though, I had something in mind like <a href="http://www.ryanheise.com/cube/speed.html">Ryan Heise's cube simulator</a> Compromise led to the current code.
The most difficult part, I'd say, was creating all six faces in a tradeoff between individual code per face and a macro for all of them; the macro won. 27 blocks were too inefficient, and so I resorted to a face assembly line: create a face, add color, stamp out ridges, rotate into place, and move it somewhere interesting. Unfortunately, adding reflections to the faces took too much space, so I had to leave it out; reflection and mirrors were the main concern for me, after the size restriction... Overall, though, I'm happy that I could fill up every pixel with a cube.