Why won't the End Portal I built in creative work?

Solution 1:

When building an End Portal by yourself, there are several pitfalls to avoid.

1. The portal must be exactly 3X3 blocks large, meaning you need 12 End Portal Frame blocks.

2. You need to place an Eye of Ender into each block.

3. The End Portal frames must face the center. This is the tricky one. End Portal Frames have 8 block states, two for each cardinal direction (with/without eye), even though the texture only has two orientations ("wavy" side, "spike" side). The be a valid portal, the blocks on the north side need to face south, the ones on the east must point west, and so on.

   When you place an end portal frame, it will point towards you (similar to pistons). To ensure a valid portal, you can place the blocks while standing in the center, facing outwards.

You also need the last eye of ender to be facing inwards for the portal to work.

Solution 2:

When you create a portal, try doing it while you are in the middle and placing the blocks all around you.