I've been trying to figure out how to create a 2x2 piston door that is flush with the wall on both sides and has no visible redstone (from either side of the door at any point). This would preferably be activated with a button toggle from either side and work ideally in vanilla Minecraft 1.7.10. I have not managed to figure this out myself so I thought I would ask here. My assumption is it would need to have the pistons be powered from below but I'm unsure how to go about it.
Sound's like you're asking about a hipster door, seen in this video by Reversed Gravity. The idea of these is that everything is flush with a 1 wide wall, where all the restone is beneath the floor. This design is showcased as 1-wide, but it can be expanded infinitely due to its tileable nature
As far as I can tell, this is the most recent and compact design, but feel free to correct me.
As per Fabian's request, here's a screenshot with a slightly modified design so it's 1.15 compatible:
Two things to note:
- The red arrows on the blocks are a tweak from a texture pack, they are observers with the arrows telling you which direction they should be facing. The same with the sticky pistons
- The observer facing down on the bottom left has a piece of redstone dust on it, this is a modification of the original design because of a change that stopped powered blocks from updating observers
- is a 2×2 door
- is flush with a 1 wide wall and the floor
- has no visible redstone (if the floor and walls are actually opaque, the glass is just here for demonstration)
- can be activated by either one of four pressure plates (and can very easily be extended to any other input)
- works in Minecraft 1.7.10, 20w18a, 1.15.2 and probably even 1.0
- has a 0 tick opening phase and a 0 tick closing phase, both starting instantly when the input turns on/off
The only issue is that you are very limited in the selection of blocks for the door. Only actual doors work properly. Alternatively, you could also use fence gates on the lower two blocks and air on the upper two, but then the door does not protect e.g. against skeletons shooting at you through it.
Also, I wouldn't really call this a "piston door", but that's just a minor detail. ;)