Automatic Nether Portal is used to enter into the Nether and you can also exit Nether using the Nether Portal.
In this guide, you will learn how to make an Automatic Nether Portal.
You will have to start by placing the obsidian blocks as shown in the image below. And then place two blocks of iron at the back side and two dispensers at the top of iron blocks.
Add more iron blocks at the top of dispensers and also on the sides as shown in the image below.
Add redstone torch and redstone dust at the top of these iron blocks.
Place a piston and observer on the other side as shown in the image below. And then use the redstone dust to connect the observer.
Go on the front side of the portal and place a lever on it. Add flint and steel in one dispenser and water bucket in the other dispenser.
Your Nether Portal work is fully functional now. Pull the lever down to make it work.