Build a 4×5 obsidian frame for a Nether portal
Leave the corners empty
Use flint and steel to light the portal
Enter the purple portal field to travel to the Nether
Build a 5×5 obsidian frame for an End portal
Place 12 Eye of Ender in the frame blocks
Enter the activated End portal to travel to the End
Build a 2×3 obsidian frame for a custom portal in creative mode
Use a portal mod or command to activate custom portals
Build a water-filled frame with a conduit for an ocean-themed portal effect
Use commands or mods to create portals to custom dimensions