I cannot seem to solve the last screen.

The only colour that makes a difference to begin with is green (makes the blue flowers green).
Next, only blue works (removes blue tones from green to make yellow).
Next, I can add and remove green (switching between yellow and green) by the same methods, or I can add red(/orange? logically it would be red, but the pipes looks rather orange) to the yellow and get orange.
Adding red to blue or green does nothing.
When on orange, the colours cannot be changed, and I don't see how to proceed. The hose/pipe(?) doesn't seem to accept any of the colours I managed to produce (blue, green, yellow, orange), but blinks red and shakes for all four.

So far, so good. When you managed to get the tree orange, you have to mix the colour in the pipe. Press green and then blue. That should create yellow in the pipe. Pressing the button now takes the yellow out of orange and leaves you with red. This is what you need.

But I agree, this "logic" puzzle hardly makes much sense when it comes to the effects of the buttons or why anyone should ever build such a stupidly complicated machine in the first place.

I felt the same way about the screen before it being affected by the *previous* screen's items. (trying to avoid spoilers ).

I've also seen complaints about the movie reel icon suddenly stopping during the "action" sequences. The argument was that the game's mechanic (of waiting during an animation) changed mid-game, and the player couldn't have known.

This was the only time I got stuck. It's especially confusing since no other item affects something in another screen. Overall, I'm very disappointed with the puzzles. There are mechanics like the acorn to tree one that are introduced and never used again. And that was exactly the kind of puzzle I was expecting to see most.

It really is strange how game mechanics were introduced and then abandoned or completely changed throughout the rest of the game. That acorn screen was perfectly done, and so organic and elegant in its use of the goggles and the environment. It's a shame they dropped that design in favor of the color-matching mechanic. There are glimpses of it later on, but nothing nearly as well integrated.

Sorry to bump this, but I just finished the game. The above is not the case, there is no effect change during the puzzle: you could always mix colours there, but given the input colours (orange, green and blue), green and blue are the only two that could be mixed.

I've given a full explanation of the colour rules here:
https://www.gog.com/forum/lilly_looking_through/lilly_looking_through_full_colour_mixing_rules_guide

I agree that the acorn puzzle screen was best, and these type of puzzles should have been used way more often on other screens.

Oh bugger, now I need to replay this one to remember what the hell this discussion was about nearly a decade ago.