[Minimal Spoilers Please] Trinity Doors?

[Enderspoons]

I've played my way up to Part X so far and still have a few leftover keys, and have only found one of the doors unlocked by the King of Riddles's keys.

Have I missed something, or are all the other Trinity Key doors still up ahead? If they're in earlier parts, I would like to know which parts I should be looking in to find them.

[SmallGespenst]

If you have multiple keys, you've missed a door. There are four regular keys and a special final one, by the time you've got the fourth normal key you should have access to all four doors, I don't recall if the fourth door is before or after the fourth phone, but they're not far apart.
edit: by part X you should've passed all of the doors that aren't the special final door

[Rilgar55]

I have found 3 so far and im after the victor fight. 1 in the cathedral where the rolling barrels are, 1 right before the king of puppets and 1 (i think it was) where the flaming ball is in the factory area

[Jeff Mcsclooberdunkies]

1st. workshop factory, before the area with the orange tubes. where you find the coal shovelling puppet, near behind the area w the 3 puppets waiting w the chest.

2nd. cathedral area take the elevator up then head to the falling electric balls. there is a ladder where the fist ball falls then, continue on past where the ball rolls and the door is on the left.

3rd. before the king of puppets area below the swinging chandelier on fire.

4th. krat central station lobby. before you open the main door to leave the station to the left is a staircase, head down and there is a trinity door.