For the longest time, I've wanted a 4x4 Spiral Door in Minecraft. But I never found one that had the full spiral, with no two blocks moving at the same time. I realized I would have to invent one myself. When I began, I couldn't figure out how to make it work, and I gave up for a while. But one day, I looked at the abandoned project, and with greater redstone knowledge and experience, I had an idea how to solve it! And now, I present to you what I believe to be the First 4x4 Spiral Door in Minecraft history!

This door is considerably compact in 2 directions, being 8 blocks tall, thus fitting withing the piston layout. It is only 3 blocks thick, which used to be the best you could hope for with a 4x4 piston door. It is however 18 blocks wide, which I feel most likely has room for improvement, bringing the full footprint to 8x3x18. I don't count the carpet on top, because that is just there to silence the note block. It might also be possible to make it 1 tick faster, but I'm not sure about that.

The input location (green concrete) can be attached to form both sides of the door. I hooked it to note blocks you can click to open and close the door. I urge you to download this this door and see the beautiful opening and closing for yourself!

Lastly, I challenge you to build a more compact 4x4 spiral door if you can.