Since MINECON has announced the incoming update for the nether, you shall be prepared to start the journey a bit ahead, maybe with fancy redstone technology. Here is the complete hidden stylish portal with a simple redstone design, but this one has EXTREME SPEED! Got fastest possible opening / closing as well as most compact size for a 3x3 hidden portal, IMO, and any challenge is accepted! (beat me if you can :p)
It is kinda perfectly tuned with some ingenious coincidences, except you may hate observer block because people could think it makes things lots easier and with less logical thinking. I personally joy to tears of welcoming it after returned to play the game for like 5 years as IMO it WAS one of the greatest updates in redstone history (I know i missed lots of things), and I have already updated anything in my base with it.
How to import by structure blocks (in vanilla MC):
(Please load it 2 times after some seconds if you see water leaks, it is a bug in MC 1.14)
~ You may need to refill the left dispenser with flint-n-steel if it runs out, or to replace the water with lava in the right dispenser if you want it built in the nether.
~ You can also make it 3x2, with same size, but if you wanna make it 3x4 and wider, you may need to change the comparator at very back to a repeater (I placed it by mistake, but it does not matter for less than 4 wide).
~ Thanks to BSL shaders and Soartex resource pack for the amazing screenshots.
~ Please enjoy my creation and have fun with it in your games!